Partenaire: Fraunhofer IISB, Erlangen
Période: 2023 – 2025
Numéro du projet: FZK02P22K030

Abstrait
Development of a SiC-Avalanche-Photodiode for flame and fire detection.

Partenaire: Bundesanstalt für Materialforschung und -prüfung (BAM), German Federal Institute for Materials Research and Testing
Période: 2021 – 2024
Numéro du projet: Landwirtschaftliche Rentenbank, 925486

Abstrait
Truffles are regarded as delicacies all over the world. However, only few can afford. The price mainly is driven by the laborious harvesting method. Thoroughly trained sniffer dogs relatively ineffectively try to find the truffles in the ground. The present project aims to the development of an innovative electronic truffle detector and tries to offer an affordable and effective instrument for truffle harvesting. The scientific approach is to reliably detect the ultraviolet light emission of the seasoned truffle’s odor signature ((CH3)2S) while exposed to ozone. An inexpensive method of truffle harvesting would allow forest owners a more sustainable forest cultivation. Today the only means of income is the sales of wood. If additionally truffles could be easily harvested and sold, this would allow a more eco friendly cultivation of the threes, not only focussing on fast growing and well selling wood.

Partenaire: sglux GmbH
Research project within the 20zwanzig initiative « Advanced UV for life »
Période: 2016 – 2021
Numéro du projet: BMBF 03ZZ0123

Abstrait
Within the UV-Aging project experimental setups and scientific method are developed to allow a reliable estimation of the degradation behavior of LED and photodiodes as well as components used in these products (glass, diffusors, reflectors, glues, etc.). In the beginning a UV-Aging chamber will be constructed which allows the control of UV light (UV-A, B & C), temperature (up to 170°C) and humidity (95% r.h.).

Partenaire: Leibniz Ferdinand Braun Institut für Höchstfrequenztechnik (FBH), Leibniz Institut für Kristallzüchtung (IKZ), sglux GmbH
Période: 2016 – 2019
Numéro du projet: BMBF 03ZZ0119A

Abstrait
This project aims at the development of optics, electronics and software for miniaturized SiC UV spectrometers and camera modules. sglux as the first company worldwide is working on a new product family of Silicon Carbide (SiC) based UV spectrometers (up to 1024 pixel resolution). The advantage of such UV spectrometers results from the extreme radiation hardness and very high visible blindness of SiC compared with Silicon (Si) based UV spectrometers leading to negligible degradation and zero stray light effects caused by visible light. This new spectrometer technology allows precise UV spectrometry also at presence of strong visible light such as UV measurements in the bright sun (e.g. UV Index spectroscopy) or under room light. Another advantage of the SiC UV spectrometer results from the high radiation hardness and low dark current of this material. These features lead to a broader dynamic range of the spectrometer compared with conventional Si based spectrometers. Spectrometers with a 128 pixel resolution are available for evaluation purpose.

Partenaire: Physikalisch-Technische Bundesanstalt in Braunschweig et Berlin (PTB) et sglux GmbH
Période: 2014 – 2019

Abstrait
Measurement and calibration facilities and calibration methods for high UV irradiation will be established within this project. These methods will accord to the calibration procedures of the Physikalisch-Technische Bundesanstalt (PTB) and will allow sglux to offer novel industry-based calibration services. Hereby the project is focussing on the UV curing industry. Based on results of a corporate BMWi ZIM project, reference radiometers and standard sources with high UV irradiation will be optimized for this application field.

Partenaire: University of Freiberg and sglux GmbH
Période: 2017 – 2018

Abstrait
The UV-Index according to ISO 17166 is a measure of the risk of sunburn (erythema solare) at a given solar irradiance. Governmental meteorological institutes measure the UV-Index with spectroradiometers. Due to high investment and maintenance costs of these spectroradiometers, the use of small, rugged and low maintenance UV-Index-Radiometers should be a matter of evaluation, in particular when meteorological networks are planned to be extended.
To evaluate the performance these UV-Index-Radiometers, basically the measurement uncertainty needs to be investigated and compared with the measurement uncertainty obtained by spectroradiometers. Egli et al.¹ report the typical UV-Index-spectrometer measurement uncertainty with ± 5 %. To investigate the measurement uncertainty of UV- Index-Radiometers, a bundle of 2073 different sun spectra with a range from UVI 0.5 until UVI 13.5 was used. They were traceably obtained at different places at the earth where the solar situation was influenced by latitude, altitude, season and daytime. Using the formula reported by ISO 17166 the UV-Index was calculated for each of the different sun spectra. Subsequently spectral responsivity curve of seven different UV-Index-Radiometers (manufactured by sglux GmbH) was integrated with the 2073 different sun spectra (according to ISO 17166) and in total 14,511 different UV-Indices were calculated. The differences of spectral responsivity of the seven candidates result from inevitable production tolerances of the UV-Index-Radiometers. These 14,511 different UV-Indices obtained by the UV-Index- Radiometer were compared with the related UV-Indices calculated by the formula stated in ISO 17166.
As a result we could demonstrate that the spectral responsivity variance of the seven different UV-Index-Radiometers did not result a measurable influence on the measurement uncertainty. However, we saw an influence caused by the different sun spectra. In particular at extremely low UV-Indices of below 0.5 the measurement uncertainty increased. We saw that this measurement uncertainty follows a definable rule which allowed us to develop a gain matrix programmable into the radiometer’s firmware. After applying of this matrix the measurement uncertainty could be reduced down to ± 5 %, also for extremely low UV-Index values.
Accordingly, the study shows that the measurement uncertainty of the sglux UV-Index- radiometers is at the same level as reported from UV-Index-spectroradiometers. This result encourages to expand the investigation into the area of the UV-Index-Radiometers field of view (FOV). The ISO 17166 standard claims a FOV close to the cosine curve. If this FOV investigation would also result good results compared with UV-Index-Spectrometers one may regard the UV-Index-Radiometers as a reliable completion or even substitution of the spectroradiometers. This would create new opportunities to measure the UV-Index in regions where skilled personnel needed to maintain the spectroradiometers is not available.

¹Egli et al. Quality assessment of solar UV irradiance measured with array spectroradiometers, Atmos. Meas. Tech., 9, 1553–1567, 2016

Partenaire: sglux GmbH
Période: 2015
Numéro du projet: BMBF 03ZZ0109

Abstrait
Before starting this project no laboratory worldwide performed traceable calibration chains for mobile UV reference radiometers. Our work aimed at a scientific evaluation and completion of UV calibration chains realizing a PTB traceability. This goal was reached by systematic evaluation, improvement and completion of an existing measurement method. As a result we now present as the first laboratory worldwide a traceable calibration chain in the ultraviolet region. This new method will be applied by the members of the “advanced UV for life” project where the method serves to determine properties of the new products planned (mainly UV LED) by means of a traceable measurement. Furthermore, this new method will by applied by sglux to determine the properties of own products and products of third parties by means of calibration service.

Partenaire: sglux GmbH
Période: 2011-2013
Numéro du projet: BMWi ZIM EP 102409

Abstrait
A 128 pixel SiC UV spectrometer with a wavelength resolution of 2.3nm/pixel was development. The advantage of such kind of UV spectrometers result from the extreme radiation hardness and very high visible blindness of SiC compared with Si based UV spectrometers leading to zero stray light effects caused by visible light. This new spectrometer technology allows precise UV spectrometry in the presence of strong visible light such as UV measurements in the bright sun or under room light. Another advantage of the SiC based UV spectrometer results from the high radiation hardness and low dark current of this material. This features lead to a broader dynamic range of the spectrometer compared with conventional Si based spectrometers.

Partenaire: Physikalisch-Technische Bundesanstalt in Braunschweig et Berlin (PTB) et sglux GmbH
Période: 2010 – 2012
Numéro du projet: BMWi ZIM 2194602RR9

Abstrait
Processes like UV water purification or UV hardening require high intensity UV radiation where a traceable calibration did not exist. German sglux GmbH together with PTB (Physikalisch-Technische Bundesanstalt, German national metrology institute) developed the world’s first traceable calibration standard for high irradiation level, in particular for UV water purification sensor calibration

Publications
B. Barton¹, P. Sperfeld¹, A. Towara¹, G. Hopfenmueller²,
¹Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), 4.1 Photometry and Applied Radiometry, Braunschweig, Germany, ²sglux GmbH, Berlin, Germany
« Developing and setting up a calibration facility for UV sensors at high irradiance rates »
EMEA Regional Conference, Karlsruhe, Germany (2013)

P. Sperfeld¹, B. Barton¹, S. Pape¹, G. Hopfenmueller²,
¹Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), 4.1 Photometry and Applied Radiometry, Braunschweig, Germany, ²sglux GmbH, Berlin, Germany
« Traceable spectral irradiance measurements at UV water disinfection facilities »
EMEA Regional Conference, Karlsruhe, Germany (2013)

G. Hopfenmueller¹, T. Weiss¹, B. Barton², P. Sperfeld², S. Nowy², S. Pape², D. Friedrich², S. Winter², A. Towara², A. Hoepe², S. Teichert²,
¹sglux GmbH, Berlin, Germany, ²Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), 4.1 Photometry and Applied Radiometry, Braunschweig, Germany
« PTB traceable calibrated reference UV radiometer for measurements at high irradiance medium pressure mercury discharge lamps »
EMEA Regional Conference, Karlsruhe, Germany (2013)

P. Sperfeld¹, B. Barton¹, S. Pape¹, A. Towara¹, J. Eggers², G. Hopfenmueller³,
¹Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), Germany, ²DVGW-Technologiezentrum Wasser, Karlsruhe, Germany, ³sglux GmbH, Berlin, Germany
« Spectral irradiance measurement and actinic radiometer calibration for UV water disinfection »
Metrologia, issue 51 (2014), S. 282-288.

P. Sperfeld¹, B. Barton¹, S. Pape¹, A. Towara¹, J. Eggers², G. Hopfenmueller³,
¹Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), Germany, ²DVGW-Technologiezentrum Wasser, Karlsruhe, Germany, ³sglux GmbH, Berlin, Germany
« Spectral Irradiance Measurement and Actinic Radiometer Calibration for UV Water Disinfection »
Proceedings of NEWRAD 2014, edited by S. Park, P. Kaerhae and E. Ikonen. (Aalto University, Espoo, Finland 2014) p. 128.

Partenaire: Physikalisch-Technische Bundesanstalt in Braunschweig et Berlin (PTB) et sglux GmbH
Période: 2011
Numéro du projet: BMWi ZIM 2194602RR9

Abstrait
For monitoring high UV irradiance, silicon carbide (SiC) based photodiodes are used. This project characterized novel SiC UV photodiodes in terms of their spectral and integral responsivity. Special attention was paid to the aging behavior of the photodiodes due to high UV irradiance. Artificial aging of the samples were performed by illumination with a high power medium pressure mercury discharge lamp. After burn in no degradation could be measured.

Publications
S. Nowy¹, B. Barton¹, S. Pape¹, P. Sperfeld¹, D. Friedrich¹, S. Winter¹, G. Hopfenmueller², T. Weiss²,
¹Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), 4.1 Photometry and Applied Radiometry, Braunschweig, Germany, ²sglux GmbH, Berlin, Germany

« Characterisation of SiC photodiodes for high irradiance UV radiometers »
Proceedings of NEWRAD2011, edited by S. Park and E. Ikonen. (Aalto University, Espoo, Finland, 2011) p. 203.

Partenaire: Physikalisch-Technische Bundesanstalt in Braunschweig et Berlin (PTB) et sglux GmbH
Période: 2011
Numéro du projet: BMWi ZIM 2194602RR9

Abstrait
A detailed study of different properties of UV diffusers was performed. Diffusers are essential components of UV radiometers used as transfer standards. They improve the insensitivity to differing radiation situations.

Publications
Barton¹, B., Sperfeld¹, P., Nowy¹, S., Towara¹, A., Hoepe¹, A., Teichert¹, S., Hopfenmueller², G., Baer³, M. and Kreuzberger³, T.
¹Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), 4.1 Photometry and Applied Radiometry, Braunschweig, Germany, ²sglux GmbH, Berlin, Germany, ³SGIL Silicaglas GmbH, Langewiesen, Germany

« Characterisation of new optical diffusers used in high irradiance UV radiometers »
Proceedings of NEWRAD2011, edited by S. Park and E. Ikonen. (Aalto University, Espoo, Finland, 2011) p. 278.

Partenaire: Leibniz Ferdinand Braun Institut für Hoechstfrequenztechnik (FBH), Leibniz Institut für Kristallzuechtung (IKZ), sglux GmbH
Période: 2008- 2010
Numéro du projet: BMWi ZIM 2194601DB9

Abstrait
Highly efficient polytype 4H silicon carbide (4H-SiC) p–n diodes for ultraviolet (UV) light detection have been fabricated, characterized, and exposed to high-intensity mercury lamp irradiation (up to 17 mW/cm²). The behavior of the photocurrent response under UV light irradiation using a low-pressure mercury UV-C lamp (4 mW/cm²) and a medium-pressure mercury discharge lamp (17 mW/cm²) has been studied. Long-term UV photoaging tests had been performed for up to 22 months. Results demonstrate the robustness of SiC photodiodes against UV radiation. The devices under test showed an initial burn-in effect, i.e., the photocurrent response dropped by less than 5% within the first 40 h of artificial UV aging. Such burn-in effect under UV stress was also observed for previously available polytype 6H silicon carbide (6H–SiC) p–n photodetectors. After burn-in, no measurable degradation has been detected, which makes the devices excellent candidates for high irradiance UV detector applications.

Publications
D. Prasai¹, W. John¹, L. Weixelbaum¹, O. Krueger¹, G. Wagner², P. Sperfeld³, S. Nowy³, D. Friedrich³, S. Winter³ and T. Weiss⁴,
¹Ferdinand-Braun-Institut, Leibniz-Institut fuer Hoechstfrequenztechnik, Berlin, Germany, ²Leibniz-Institut fuer Kristallzuechtung, Berlin, Germany, ³Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), 4.1 Photometry and Applied Radiometry, Braunschweig, Germany, ⁴sglux GmbH, Berlin, Germany

« Highly reliable Silicon Carbide photodiodes for visible-blind ultraviolet detector applications »
J. Mater. Res., first view (2012).

Partenaire: Technische Hochschule Wildau, sglux GmbH
Période: 2008-2009
Numéro du projet: BMBF 13N9586

Abstrait
Electronic and photoelectrical properties of semiconducting titanium dioxide layers had been investigated and improved.

Publications
C. Nitschke
« Electronic and photoelectrical properties of semiconducting titanium dioxide layers »
Beuth Hochschule für Technik, Master Thesis, 2009

Gabriel Hopfenmüller, Dr. Niklas Papathanasiou, sglux GmbH, Berlin, Germany

InterAqua Japan 01. – 03.02.2023
Approaches of LED in-line measurements and its traceable calibration

Abstrait
UV measurement at UV LED arrays.

Michael Schraml¹, Alexander May¹, Dr. Tobias Erlbacher¹, Dr. Niklas Papathanasiou², Dr. Tilman Weiss²,
¹Fraunhofer IISB, Erlangen, Germany
²sglux GmbH, Berlin, Germany

Towards SiC-Based VUV Pin-Photodiodes – Investigations on 4H-SiC Photodiodes with Shallow Implanted Al Emitters

Abstrait
4H silicon carbide (SiC) based pin photodiodes with a sensitivity in the vacuum ultraviolet spectrum (VUV) demand newly developed emitter doping profiles. This work features the first ever reported 4H-SiC pin photodiodes with an implanted p-emitter and a noticeable sensitivity at a wavelength of 200 nm. As a first step, Aluminum doping profiles produced by low energy ion implantation in 4H-SiC were characterized by secondary-ion mass spectrometry (SIMS). Photodiodes using these shallow emitters are compared to one with a deep p-emitter doping profile employing IV characteristics and the spectral response. SIMS results demonstrate the possibility of shallow Alimplantation profiles using low implantation energies with all emitter profiles featuring characteristic I-V results. For some shallow doping profiles, a meassurable signal at the upper limit of the VUV spectrum could be demonstrated, paving the way towards 4H-SiC pin photodiodes with sensitivities for wavelengths below 200 nm.

Dr. Tilman Weiss, sglux GmbH, Berlin, Germany

How to determine the right UV sensor for flame detection?

Abstrait
The present article informs about different approaches using UV photodetectors for the detection of a combustion flame (natural gas, hydrogen or oil).

Ruben Epping¹, Lilly Bliesener¹, Dr. Tilman Weiss², Matthias Koch¹, *
¹Division of Organic Trace Analysis and Food Analysis, Bundesanstalt für Materialforschung und -Prüfung, Berlin, Germany
²sglux GmbH, Berlin, Germany
*Authors to whom correspondence should be addressed.

Marker Substances in the Aroma of Truffles

Abstrait
The aim of this study was to identify specific truffle marker substances within the truffle aroma. The aroma profile of different truffle species was analyzed using static headspace sampling with gas chromatography mass spectrometry analysis (SHS/GC-MS). Possible marker substances were identified, taking the additional literature into account. The selected marker substances were tested in an experiment with 19 truffle dogs. The hypothesis “If trained truffle dogs recognize the substances as supposed truffles in the context of an experiment, they can be regarded as specific” was made. As it would be nearly impossible to investigate every other possible emitter of the same compounds to determine their specificity, this hypothesis was a reasonable approximation. We were interested in the question of what it is the dogs actually search for on a chemical level and whether we can link their ability to find truffles to one or more specific marker substances. The results of the dog experiment are not as unambiguous as could have been expected based on the SHS/GC-MS measurements. Presumably, the truffle aroma is mainly characterized and perceived by dogs by dimethyl sulfide and dimethyl disulfide. However, as dogs are living beings and not analytical instruments, it seems unavoidable that one must live with some degree of uncertainty regarding these results

Luther W. Beegle et al.
Space Sci Rev (2021) 217:58

Perseverance’s Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) Investigation

Abstrait
The Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) is a robotic arm-mounted instrument on NASA’s Perseverance rover. SHERLOC has two primary boresights. The Spectroscopy boresight generates spatially resolved chemical maps using fluorescence and Raman spectroscopy coupled to microscopic images (10.1 μm/pixel). The second boresight is a Wide Angle Topographic Sensor for Operations and eNgineering (WATSON); a copy of the Mars Science Labora- tory (MSL) Mars Hand Lens Imager (MAHLI) that obtains color images from microscopic scales (∼13 μm/pixel) to infinity. SHERLOC Spectroscopy focuses a 40 μs pulsed deep UV neon-copper laser (248.6 nm), to a ∼100 μm spot on a target at a working distance of ∼48 mm. Fluorescence emissions from organics, and Raman scattered photons from organics and minerals, are spectrally resolved with a single diffractive grating spectrograph with a spectral range of 250 to ∼370 nm. Because the fluorescence and Raman regions are natu- rally separated with deep UV excitation (<250 nm), the Raman region ∼ 800 – 4000 cm−1 (250 to 273 nm) and the fluorescence region (274 to ∼370 nm) are acquired simultaneously without time gating or additional mechanisms. SHERLOC science begins by using an Aut- ofocus Context Imager (ACI) to obtain target focus and acquire 10.1 μm/pixel greyscale images. Chemical maps of organic and mineral signatures are acquired by the orchestration of an internal scanning mirror that moves the focused laser spot across discrete points on the target surface where spectra are captured on the spectrometer detector. ACI images and chemical maps (< 100 μm/mapping pixel) will enable the first Mars in situ view of the spa- tial distribution and interaction between organics, minerals, and chemicals important to the assessment of potential biogenicity (containing CHNOPS). Single robotic arm placement chemical maps can cover areas up to 7x7 mm in area and, with the < 10 min acquisition time per map, larger mosaics are possible with arm movements. This microscopic view of the organic geochemistry of a target at the Perseverance field site, when combined with the other instruments, such as Mastcam-Z, PIXL, and SuperCam, will enable unprecedented analysis of geological materials for both scientific research and determination of which sam- ples to collect and cache for Mars sample return.

Dr. Tilman Weiss, sglux GmbH, Berlin, Germany

TOCONs for the detection of fire and combustion burner flames

Abstrait
The standard sglux TOCONs are featured by a relatively high time constant that extends from 30 ms (low sensitivity TOCONs) until 80 ms (high sensitivity TOCONs). Most of the TOCON applications benefit from this high time constant because usually the TOCON’s application is to measure a UV irradiation that slowly changes. Such applications are e.g. the control of UV disinfection and UV curing sources. Short changes of signal caused by electromagnetic or high frequency influences are averaged – which is a benefit. However, looking at flame detection in heaters or looking at fire detection applications this relatively high time constant may cause problems. The present report presents opportunities to reduce the dead time of the TOCONs.

Bielefeld, S.E., TU Delft Electrical Engineering, Mathematics and Computer Science

Master Thesis

Abstrait
As a contribution to the decarbonisation of domestic heating, the graduation project investigates the feasibility of the application of UV sensor technology for flame detection and flame monitoring in hydrogen-powered domestic gas boilers. The research includes empirical studies and an analytical approach to describe influences on the sensor signal strength.

Dr. Tilman Weiss, sglux GmbH, Berlin, Germany

UV sensors for hydrogen flame detection

Abstrait
Pursuing the goal of decarburization of the energy use, the substition of petroleum gas by hydrogen gas produced with renewable energy is a very promising approach.

This requires a certain modification of the heaters. A major change will be the modification of the EN298 compliant flame sensing feature. Currently, sensing petroleum gas flames, electric ionization sensors are used – a rugged, reliable and inexpensive method. However, if hydrogen gas is added to the petroleum gas or if the gas entirely consists of hydrogen these ionization sensors can not be further applied. The reason is a changed reaction kinetics where the ionization effect can not be detected by these conventional sensors. This challenge can be mastered by use of opto-electronic UV sensors. These sensors reliably detect all kind of flames while “seeing” their characteristic emission spectrum in the ultraviolet light range. As UV sensors are more expensive than ionization detectors currently the UV sensors are only applied in highly priced industrial burners but not in household burners. However, according the current state of the knowledge, no other method than opto-electronic UV sensors are able to reliably detect a hydrogen flame.

Since 2006 we produce the TOCONs ABC1 and ABC2 for the EN298 compliant detection of petroleum gas flames in household burners. Our new TOCON_F series is designed for the detection of hydrogen flames.

The difference of the new TOCON_F to the standard ABC1 and ABC2 TOCONs is a reduced off dead-time. This off dead-time occurs with the standard TOCONs when they are saturated and can extend to several 100 milliseconds. The TOCON_F with its logarithmic amplifier shrinks this dead-time to less than 70 milliseconds. Accordingly the reaction time after the flame’s (unwanted) distinction could be strongly increased. Even if the standard TOCONs ABC1 and ABC2 are fast enough (compliant with EN298) to be applied in flame sensing modules (EN298 claims a reaction time of less than 1000 milliseconds) – the requirements of the EN298 standard could be tightened in the future. The reason of this assumption is the significantly higher rate of spread and ignition range of a hydrogen flame compared with a petroleum gas flame. Hence a UV sensor module that works with a TOCON_F offers shorter reaction times than currently required by the standard. This makes these flame sensing modules future-proof in case of a possible revision of the standard.

Jean-Maurice Cadet¹, Thierry Portafaix¹, Hassan Bencherif¹², Kévin Lamy¹, Colette Brogniez³, Frédérique Auriol³, Jean-Marc Metzger⁴, Louis-Etienne Boudreault⁵, Caradee Yael Wright⁶⁷
¹LACy, Laboratoire de l’Atmosphère et des Cyclones (UMR 8105 CNRS, Université de La Réunion, Météo-France), 97744 Saint-Denis de La Réunion, France.
²School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4041, South Africa.
³Laboratoire d’Optique Atmosphérique, Université Lille, CNRS, UMR 8518, F-59000 Lille, France.
⁴Observatoire des Sciences de l’Univers de la Réunion, UMS 3365, 97744 Saint-Denis de la Réunion, France.
⁵Reuniwatt, 97490 Sainte Clotilde de la réunion, France.
⁶Department of Geography, Geo-informatics and Meteorology, University of Pretoria, Pretoria 0002, South Africa.
⁷Environment and Health Research Unit, South African Medical Research Council, Pretoria 0001, South Africa.

Int J Environ Res Public Health. 2020 Apr 21;17(8):2867. doi: 10.3390/ijerph17082867

Abstrait
Measurement of solar ultraviolet radiation (UVR) is important for the assessment of potential beneficial and adverse impacts on the biosphere, plants, animals, and humans. Excess solar UVR exposure in humans is associated with skin carcinogenesis and immunosuppression. Several factors influence solar UVR at the Earth’s surface, such as latitude and cloud cover. Given the potential risks from solar UVR there is a need to measure solar UVR at different locations using effective instrumentation. Various instruments are available to measure solar UVR, but some are expensive and others are not portable, both restrictive variables for exposure assessments. Here, we compared solar UVR sensors commercialized at low or moderate cost to assess their performance and quality of measurements against a high-grade Bentham spectrometer. The inter-comparison campaign took place between March 2018 and February 2019 at Saint-Denis, La Réunion. Instruments evaluated included a Kipp&Zonen UVS-E-T radiometer, a Solar Light UV-Biometer, a SGLux UV-Cosine radiometer, and a Davis radiometer. Cloud fraction was considered using a SkyCamVision all-sky camera and the Tropospheric Ultraviolet Visible radiative transfer model was used to model clear-sky conditions. Overall, there was good reliability between the instruments over time, except for the Davis radiometer, which showed dependence on solar zenith angle. The Solar Light UV-Biometer and the Kipp&Zonen radiometer gave satisfactory results, while the low-cost SGLux radiometer performed better in clear sky conditions. Future studies should investigate temporal drift and stability over time.

Stefan Langer, sglux GmbH, Berlin, Germany

SiC Temperature Coefficient

Abstrait
This report assigns the temperature coefficient (TC) of sglux SiC-photodiodes in relation to the incident wavelength. It demonstrates that the temperature coefficient is slightly negative for incident wavelengths below 270nm. At appox. 270nm is it almost zero and then strongly rises towards positive values with increasing wavelengths. The report further explains the physical background of this phenomena.

Dr. Tilman Weiss, sglux GmbH, Berlin, Germany

UV sensors to control UVC surface disinfection

Abstrait
Besides chemical treatment, UVC sterilization is applied to disinfect air and tools in hospitals, doctor’s offices, pharmacies as well as food and pharmaceutical production facilities and public washrooms. These applications require measurements of the UV radiation either at its place of generation or at the position of the goods to be disinfected. This procedure is crucial to ensure that a sufficient germ killing UV dose hits the goods. The report presents further details and suitable sensor and radiometer products.

Dr. Tilman Weiss, sglux GmbH, Berlin, Germany

Technical Report « Where SiC can replace discontinued GaP? »

Abstrait
For measurement applications with a peak radiation between 210 nm and 346 nm (e.g. UV sterilization lamp or combustion flame control) a SiC UV photodiode can replace a GaP photodiode without restrictions – it will even output a higher photocurrent. A SiC device irradiated with a peak radiation from 346 to 380 nm will output a lower photocurrent compared with GaP (at same active area). However, if the radiation intensity is high, e.g. curing applications at 365 nm the SiC’s current output will remain at a usable level.

Dr. Niklas Papathanasiou, sglux GmbH, Berlin, Germany

Tech Report 350°C

Abstrait
sglux announces that a new high temperature stable SiC UV Photodiode is now available. The photodiode can be permanently operated at a temperature of 350°C.

Dr. Niklas Papathanasiou, sglux GmbH, Berlin, Germany

SiC AlGaN Aging Report

Abstrait
SiC and AlGaN based UV photodiodes had been irradiated by Hg medium pressure lamps for 90 hours and a UV irradiation intensity of 60mW/cm². The SiC photodiodes showed no measurable degradation whereas the AlGaN photodiodes lost 80 % – 85 % of sensitivity.

Stefan Langer¹, Dr. Niklas Papathanasiou¹, Johanna Luise Krueger², Gabriel Hopfenmueller¹, Dr. Tilman Weiss¹
¹sglux GmbH, Berlin, Germany, ²University of Freiberg, Germany

50th Annual Conference of the Radiation Protection Association 2018, Dresden, Germany
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Abstrait
Industrial application of ultraviolet radiation requires not only the evaluation of the effectiveness for the desired process but also an assessment of hazards for the operating personnel. Therefore rules and regulations have been established for the assessment and limitation of health-related threats. A variety of instruments are available on the market for this kind of risk assessment. These devices measure the radiation weighted according to applicable regulatory standards. But the final appraisal of risks such as maximum tolerable exposure time must still be computed manually afterwards.
The new approach presented here is based on a sensor with a spectral response characteristic tailored to a specific regulatory standard. This sensor is connected to a smart-phone. An application on the smart-phone will present the measurement value but also the maximum allowed exposure time in a graphical and acoustical manner. Each radiation source or regulatory guideline requires a specific sensor characteristic for an accurate risk assessment. Therefore the system extensively checks the requirements regarding the suitability of the connected sensor for the selected regulatory norm. These measures reduce the effort and the failure rate and also lower the burden for risk assessment in daily operation.

Johanna Luise Krueger², Dr. Niklas Papathanasiou¹, Stefan Langer¹, Gabriel Hopfenmueller¹, Dr. Tilman Weiss¹
¹sglux GmbH, Berlin, Germany, ²University of Freiberg, Germany

50th Annual Conference of the Radiation Protection Association 2018, Dresden, Germany
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Abstrait
Environmental data are collected to improve health-related quality of life of citizens. The solar UV-Index provides a good indicator for reasonable sun protection measures and duration of sun light exposure for safety officers and individuals. In Germany the « Bundesamt für Strahlenschutz » manages a solar UV-measurement network to monitor the UV-Index. At ten sites distributed all over Germany spectroradiometers are operated to measure the solar spectrum. The spectroradiometers are expensive and need highly qualified personnel to be operated. Robust and low-maintenance SiC-based UV-Index-radiometers are a viable option to increase the density of this measurement network at low cost. The spectral sensitivity function of such UV-Index-radiometers must reproduce the erythemal action function according to ISO 17166 with high precision.
In this contribution we investigate the effect of production tolerances in the spectral response of SiC-based UV-Index-radiometer (SiC-UVI-radiometer) onto the precision of the measured UV-Index. This is performed by folding a large number of different sun spectra with a variety of spectral responses of actual SiC-UVI-radiometer and the erythemal action curve as defined in the ISO 17166. We can show that the measurement uncertainty of SiC-based UVI-radiometers is ±5 % and therefore in the range of spectroradiometers. We simulated UVI measurements for SiC-based UVI-radiometers with over 2000 different sun spectra and determined a discrepancy-correction-function, which allows a precise UVI-measurement.

Dr. Niklas Papathanasiou, Gabriel Hopfenmueller, Dr. Tilman Weiss
sglux GmbH, Berlin, Germany

Presentation on IoT-SNAP2018: IoT Enabling Sensing/Network/AI and Photonics Conference at
Optics & Photonics Intenational Congress OPIC 2018, Pacifico Yokohama, Yokohama, Japan

Abstrait
In this contribution we report about SiC based UV photodiodes as the core component of smart UV sensors for various medical applications. In dialysis machines the transparency of urea is monitored by a SiC UV photodiode based UV transmission measurement module. A photodiode combined with an optical filter which reproduces the erythermal action spectrum helps Lupus patients to monitor their daily dose of solar UV radiation. sglux UVC sensor “UV-Safester” is a smartphone based tool to detect harmful UV radiation at a workplace employing the ICNIRP regulation. A wireless UV sensor module monitors the UV disinfection applied by disinfection robots in operating rooms.

G. Hopfenmueller, N. Papathanasiou, T. Weiss,
sglux GmbH, Berlin, Germany

International Conference on UV LED Technologies & Applications 2018, Berlin, Germany

Abstrait
Artificial UV radiation is applied in many processes such as UV disinfection, UV curing or biological activation. Besides discharge tubes, LEDs are becoming more important for a rising number of applications in particular UV curing or medical treatment. In general, exposure to UV radiation may cause health problems such as skin aging, eye damage or skin cancer. The potential danger varies with the irradiated wavelengths and the exposure time. The limits and the spectral weighting function of the UV irradiance are given in the directive 2006/25/EC published by the European Comission. The hereby submitted lecture will introduce a radiometer that precisely evaluates the hazard potential while displaying the maximum daily exposition time at a certain measurement point. The digital SiC based UV sensor has a spectral responsivity close to the biological weighting function and is calibrated to different UV LEDs with typical half widths. The sensor can be connected to any Android smartphone.

N. Papathanasiou, G. Hopfenmüller, Michael Matalla, T. Weiss,
sglux GmbH, Berlin, Germany

Presentation on IUVA World Congress Spotlights Water Disinfection Technologies 2017, Dubrovnik, Croatia

Abstrait
In UV water purification applications UV sensors are monitoring the dosage of UV irradiation as according to ÖNORM and DVGW standards. sglux GmbH is manufacturing such sensors employing opaque synthetic quartz-glass diffusers as entrance windows. This paper investigates the influence of high-intensity UV irradiation on the transmission behavior of these diffusers. Quartz-glass and micro-porous quartz-glass were investigated. The sensors were continuously monitored while irradiated by a 1kW medium pressure Hg lamp with a total UV irradiance of 1000mW/cm² for 800 hours. Before and after the aging period the total transmissions of the diffusers were measured.

Alois W. Schmalwieser¹, Julian Gröbner², Mario Blumthaler³, Barbara Klotz³, Hugo De Backer⁴, David Bolsée⁵, Rolf Werner⁶, Davor Tomsic⁷, Ladislav Metelka⁸, Paul Eriksen⁹, Nis Jepsen⁹, Margit Aun¹⁰, Anu Heikkilä¹¹, Thierry Duprat¹², Henner Sandmann¹³, Tilman Weiss¹⁴, Alkis Bais¹⁵, Zoltan Toth¹⁶, Anna-Maria Siani¹⁷, Luisa Vaccaro¹⁸, Henri Diémoz¹⁹, Daniele Grifoni²⁰, Gaetano Zipoli²¹, Giuseppe Lorenzetto²², Boyan H. Petkov²³, Alcide Giorgio di Sarra²⁴, Francis Massen²⁵, Charles Yousif²⁶, Alexandr A. Aculinin²⁷, Peter den Outer²⁸, Tove Svendby²⁹, Arne Dahlback³⁰, Bjørn Johnsen³¹, Julita Biszczuk-Jakubowska³², Janusz Krzyscin³³, Diamantino Henriques³⁴, Natalia Chubarova³⁵, Predrag Kolarž³⁶, Zoran Mijatovic³⁷, Drago Groselj³⁸, Anna Pribullova³⁹, Juan Ramon Moreta Gonzales⁴⁰, Julia Bilbao⁴¹, José Manuel Vilaplana Guerrero⁴², Antonio Serrano⁴³, Sandra Andersson⁴⁴, Laurent Vuilleumier⁴⁵, Ann Webb⁴⁶, and John O’Hagan⁴⁷,

¹University of Veterinary Medicine, Unit of Physiology and Biophysics, Vienna, Austria, ²PMOD/WRC, Davos Dorf, Switzerland, ³Medical Univ. Innsbruck, Innsbruck, Austria, ⁴Royal Meteorological Institute of Belgium, Observations, Brussels, Belgium, ⁵Royal Belgian Institute for Space Aeronomy, Brussels, Belgium, ⁶Bulgarian Academy of Sciences, Stara Zagora, Bulgaria, ⁷Metorological and hydrological institute of Croatia, Metorological and hydrological institute of Croati, Croatia, ⁸Czech Hydrometeorological Institute, Solar and Ozone Department, Hradec Kralove, Czech Republic, ⁹Danish Meteorological Institute, Copenhagen, Denmark, ¹⁰Tartu Observatory, Tartumaa, Estonia, ¹¹Finnish Meteorological Institute, Helsinki, Finland, ¹²Météo-France, Toulouse Cedex, France, ¹³Bundesamt fur Strahlenschutz Neuherberg, Section for Optical Radiation, Neuherberg, Germany, ¹⁴sglux GmbH, Berlin, Germany, ¹⁵Aristotle University of Thessaloniki, Greece, ¹⁶Hungarian Meteorological Service, Marczell György Main Observatory, Budapest, Hungary, ¹⁷Sapienza Universita’ di Roma, Physics Department, Rome, Italy, ¹⁸ISPRA, Physical Agents Unit, Rome, Italy, ¹⁹ARPA Valle d’Aosta loc, Saint-Christophe, Italy, ²⁰LaMMA Consortium, Institute of Biometeorology of the National Research Council, Sesto Fiorentino, Italy, ²¹CNR-IBIMET, Florence, Italy, ²²ARPA di Vicenza, Vicenza, Italy, ²³National Research Council, Institute of Atmospheric Sciences and Climate, Bologna, Italy, ²⁴ENEA, Laboratory for Observations and Analyses of the Earth and Climate, Rome, Italy, ²⁵Lycée Classique de Diekirch, Computarium and meteoLCD, Diekirch, Luxembourg, ²⁶University of Malta, Institute for Sustainable Energy, Marsaxlokk, Malta, ²⁷Institute of Applied Physics of the Academy of Sciences of Moldova, Kishinev, Moldova (the Republic of), ²⁸Dutch National Health Institute (RIVM), Netherlands, ²⁹NILU – Norwegian Institute for Air Research, Kjeller, Norway, ³⁰University of Oslo, Institute of Physics, Oslo, Norway, ³¹Statens Stralevern, Monitoring and Research, Oesteras, Norway, ³²Institute of Meteorology and Water Management, Gdynia, Poland, ³³Institute of Geophysics, Polish Academy of Sciences, Warszw, Poland, ³⁴Instituto Português do Mar e da Atmosfera, Observatório Afonso Chaves, Ponta Delgada S. Miguel, Portugal, ³⁵Moscow State University, Moscow, Russian Federation, ³⁶University of Belgrade, Zemun, Serbia, ³⁷University of Novi Sad, Novi Sad, Serbia, ³⁸Slovenian Environment Agency, Ljubljana, Slovenia, ³⁹Slovakian Academy of Sciences, Tatranska Lomnica, Slovakia, ⁴⁰Spanish Meteorological Agency, Area of Atmospheric Observation Networks, Madrid, Spain, ⁴¹University of Valladolid, Valladolid, Spain, ⁴²National Institute for Aerospace Technology, Mazagon, Spain, ⁴³University of Extremadura, Department of Physics, Badajoz, Spain, ⁴⁴SMHI, Norköpping, Sweden, ⁴⁵MeteoSwiss, Atmospheric data division, Payerne, Switzerland, ⁴⁶University of Manchester, Manchester, United Kingdom of Great Britain and Northern Ireland, ⁴⁷Public Health England Centre for Radiation Chemical and Environmental Hazards, Radiation Dosimetry, Didcot, United Kingdom of Great Britain and Northern Ireland

Journal: Photochemical & Photobiological Sciences, Publisher: The Royal Society of Chemistry.

Abstrait
The UV Index was established more than 20 years ago as a tool for sun protection and health care. Shortly after its introduction, UV Index monitoring started in several countries either by newly acquired instruments or by converting measurements from existing instruments into the UV Index. The number of stations and networks has increased over the years. Currently, 160 stations in 25 European countries deliver online values to the public via the Internet. In this paper an overview of these UV Index monitoring sites in Europe is given. The overview includes instruments as well as quality assurance and quality control procedures. Furthermore, some examples are given about how UV Index values are presented to the public. Through these efforts, 57% of the European population is supplied with high quality information, enabling them to adapt behaviour. Although health care, including skin cancer prevention, is cost-effective, a proportion of the European population still doesn’t have access to UV Index information.

P. Sperfeld¹, B. Barton¹, S. Pape¹, A. Towara¹, J. Eggers², G. Hopfenmueller³,
¹Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), Germany, ²DVGW-Technologiezentrum Wasser, Karlsruhe, Germany, ³sglux GmbH, Berlin, Germany

Metrologia, 51 (2014), S. 282-288.

Abstrait
In a joint project, sglux and PTB investigated and developed methods and equipment to measure the spectral and weighted irradiance of high-efficiency UV-C emitters used in water disinfection plants. A calibration facility was set up to calibrate the microbicidal irradiance responsivity of actinic radiometers with respect to the weighted spectral irradiance of specially selected low-pressure mercury and medium-pressure mercury UV lamps. To verify the calibration method and to perform on-site tests, spectral measurements were carried out directly at water disinfection plants in operation. The weighted microbicidal irradiance of the plants was calculated and compared to the measurements of various actinic radiometers.

P. Sperfeld¹, B. Barton¹, S. Pape¹, A. Towara¹, J. Eggers², G. Hopfenmueller³,
¹Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), Germany, ²DVGW-Technologiezentrum Wasser, Karlsruhe, Germany, ³sglux GmbH, Berlin, Germany

Proceedings of NEWRAD 2014, edited by S. Park, P. Kaerhae and E. Ikonen. (Aalto University, Espoo, Finland 2014) p. 128.

Abstrait
In a joint project, sglux and PTB investigated and developed methods and equipment to measure the spectral and weighted irradiance of high-efficiency UV-C emitters used in water disinfection plants. A calibration facility was set up to calibrate the microbicidal irradiance responsivity of actinic radiometers with respect to the weighted spectral irradiance of specially selected Hg low-pressure and medium-pressure UV radiators. To verify the calibration and to perform on-site tests, spectral measurements have been carried out directly at water disinfection plants in operation. The weighted microbicidal irradiance of the plants was calculated and compared to the measurements of various actinic radiometers.

B. Barton¹, P. Sperfeld¹, A. Towara¹, G. Hopfenmueller²,
¹Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), 4.1 Photometry and Applied Radiometry, Braunschweig, Germany, ²sglux GmbH, Berlin, Germany

EMEA Regional Conference, Karlsruhe, Germany (2013)

Abstrait
PTB provides spectral irradiance calibrations traceable to national primary standards and the SI system. A transfer standard source for high UV irradiances has been constructed and characterized. A medium pressure Hg lamp and a low pressure Hg lamp provide different spectra at different irradiance levels. The system might serve as a calibration facility for DVGW & ÖNORM conform UV sensors. Calibration by direct substitution to reference sensors can be carried out.

P. Sperfeld¹, B. Barton¹, S. Pape¹, G. Hopfenmueller²,
¹Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), 4.1 Photometry and Applied Radiometry, Braunschweig, Germany, ²sglux GmbH, Berlin, Germany

EMEA Regional Conference, Karlsruhe, Germany (2013)

Abstrait
PTB provides spectral irradiance calibrations traceable to national primary standards and the SI system. Transportable spectroradiometer systems have been adapted for high UV irradiance measurements. Successful measurements at medium pressure Hg and low pressure Hg lamp facilities have been carried out. The effective microbicidal irradiances agree within 15%. 40° sensor geometry could be developed. Discussion about calibration service and support.

G. Hopfenmueller¹, T.Weiss¹, B. Barton², P. Sperfeld², S. Nowy², S. Pape², D. Friedrich², S. Winter², A. Towara², A. Hoepe², S. Teichert²,
¹sglux GmbH, Berlin, Germany, ²Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), 4.1 Photometry and Applied Radiometry, Braunschweig, Germany

EMEA Regional Conference, Karlsruhe, Germany (2013)

D. Prasai¹, W. John¹, L. Weixelbaum¹, O. Krueger¹, G. Wagner², P. Sperfeld³, S. Nowy³, D. Friedrich³, S. Winter³ and T. Weiss⁴,
¹Ferdinand-Braun-Institut, Leibniz-Institut fuer Hoechstfrequenztechnik, Berlin, Germany, ²Leibniz-Institut fuer Kristallzuechtung, Berlin, Germany, ³Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), 4.1 Photometry and Applied Radiometry, Braunschweig, Germany, ⁴sglux GmbH, Berlin, Germany

J. Mater. Res., first view (2012).

Abstrait
Highly efficient polytype 4H silicon carbide (4H-SiC) p–n diodes for ultraviolet (UV) light detection have been fabricated, characterized, and exposed to high-intensity mercury lamp irradiation (up to 17 mW/cm²). The behavior of the photocurrent response under UV light irradiation using a low-pressure mercury UV-C lamp (4 mW/cm²) and a medium-pressure mercury discharge lamp (17 mW/cm²) has been studied. We report on long-term UV photoaging tests performed for up to 22 mo. Results demonstrate the robustness of SiC photodiodes against UV radiation. The devices under test showed an initial burn-in effect, i.e., the photocurrent response dropped by less than 5% within the first 40 h of artificial UV aging. Such burn-in effect under UV stress was also observed for previously available polytype 6H silicon carbide (6H–SiC) p–n photodetectors. After burn-in, no measurable degradation has been detected, which makes the devices excellent candidates for high irradiance UV detector applications.

S. Nowy¹, B. Barton¹, S. Pape¹, P. Sperfeld¹, D. Friedrich¹, S. Winter¹, G. Hopfenmueller², and T. Weiss²,
¹Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), 4.1 Photometry and Applied Radiometry, Braunschweig, Germany, ²sglux GmbH, Berlin, Germany

Proceedings of NEWRAD2011, edited by S. Park and E. Ikonen. (Aalto University, Espoo, Finland, 2011) p. 203.

Abstrait
For monitoring high UV irradiance, silicon carbide (SiC) based photodiodes are used. In this paper we describe the characterization of the novel SiC UV photodiodes in terms of their spectral and integral responsivity. Special attention is paid to the aging behavior of the photodiodes due to high UV irradiance. Artificial aging of the samples is performed by illumination with a high power medium pressure mercury discharge lamp.

Barton¹, B., Sperfeld¹, P., Nowy¹, S., Towara¹, A., Hoepe¹, A., Teichert¹, S., Hopfenmueller², G., Baer³, M. and Kreuzberger³, T.
¹Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), 4.1 Photometry and Applied Radiometry, Braunschweig, Germany, ²sglux GmbH, Berlin, Germany, ³SGIL Silicaglas GmbH, Langewiesen, Germany

Proceedings of NEWRAD2011, edited by S. Park and E. Ikonen. (Aalto University, Espoo, Finland, 2011) p. 278.

Abstrait
Diffusers are essential components of UV radiometers used as transfer standards. They improve the insensitivity to differing radiation situations. In combination with a beam limiting aperture, a diffuser defines the irradiated area [1]. A detailed study of different properties of UV diffusers is shown.

C. Nitschke
Beuth Hochschule für Technik, Master Thesis, 2009

Master thesis 2009

Abstrait
In the present thesis electronic and photoelectrical properties of semiconducting titanium dioxide layers were measured using different measuring methods. The titanium dioxide layers had been produced using the sol-gel-process with different precursor solutions. The findings and insights gained shall be used to manipulate the structure and functionality of UV-photodiodes with titanium-dioxide-layers. Traps had been proven both by the analysis of the spectral resolution of the photocurrent and thermally stimulated luminescence. These traps are affected by the titanium dioxide-layer manufacturing process. Using the impedance spectroscopy, the UV-photodiodes inner structure, the width of the space charge layer and the electrical conduction of the titanium dioxide-layer grains and grain boundaries could be measured. Between the impedance of the UV-photodiodes and the speed of reaction a correlation could be noticed. Additionally voltage dependent current and capacity measurements had been carried out as well as thermally stimulated currents had been measured.

Th. Dittrich¹, V. Zinchuk², V. Skryshevsky², I. Urban³, O. Hilt⁴
¹Hahn-Meitner-Institut, Berlin, Germany
²Department of Radiophysics, Taras Shevchenko University, Kyiv, Ukraine
³Bundesanstalt für Materialforschung, Berlin, Germany
⁴sglux GmbH, Berlin, Germany

JOURNAL OF APPLIED PHYSICS 98, 104501 (2005)

Abstrait
Pt/TiO₂/Ti Schottky diodes were investigated by current-voltage analysis, photoresponse, and transient photocurrent(PC) in a wide temperature range. The compact TiO₂ as well as the SiO₂ passivation layers were prepared by the sol-gel technique. The Schottky-barrier height (1.2–1.3eV) was equal to the difference of the work functions of Pt and Ti. The temperature dependence of the ideality factor was interpreted in terms of a Gaussian distribution of barrier heights [J. H. Werner and H. H. Güttler, J. Appl. Phys.69, 1522 (1991)]. Space-charge-limited currents under the presence of defects with an exponential distribution were observed. Under zero-potential condition, the PC transients were practically independent of temperature and the electron drift mobility amounted to 2× 10E-4 cm² (Vs)
A screening dipole layer at the Pt/TiO₂ junction was formed under low forward and reverse potentials. Defects were generated under electron injection.