Stefan Langer, sglux GmbH, Berlin, Germany

SiC Temperature Coefficient

Zusammenfassung
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.

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)

Abstract
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.

Dr. Tilman Weiss, sglux GmbH, Berlin, Germany

Technical Report „Where SiC can replace discontinued GaP?“

Zusammenfassung
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

Zusammenfassung
Neue Hochtemperatur SiC-Photodioden erhältlich. Die Photodioden können permanent bis zu einer Temperatur von 350°C betrieben werden.
[_/su_spoiler]

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

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

Abstract
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.

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.

Abstract
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.

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

Master thesis 2009

Abstract
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.

Stefan Langer¹, Dr. Niklas Papathanasiou¹, Johanna Luise Krüger², Gabriel Hopfenmüller¹, Dr. Tilman Weiss¹
¹sglux GmbH, Berlin, Germany, ²Technische Universität Bergakademie Freiberg, Germany

50. Jahrestagung des Fachverbandes Strahlenschutz 2018, Dresden
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Zusammenfassung
Die industrielle Nutzung ultravioletter Strahlung erfordert neben der Beurteilung der Prozesswirksamkeit auch deren Bewertung hinsichtlich der Gefährdung des Bedien- und Wartungspersonals. Zu diesem Zweck sind Regelwerke entstanden, die die Durchführung der Strahlungsmessung und deren Bewertung hinsichtlich gesundheitlicher Gefahren beschreiben. Für diese Gefährdungsbeurteilung sind verschiedene Messgeräte am Markt erhältlich. Sie bestimmen die entsprechend der Norm gewichtete momentane Bestrahlungsstärke. Die Ermittlung der zulässigen maximalen täglichen Aufenthaltsdauer muss allerdings in nachfolgenden Rechenschritten erfolgen.
Ein neuartiger, mit diesem Konferenzbeitrag vorgestellter Ansatz basiert auf einem Sensor mit einer an die jeweilige Norm angepassten Empfindlichkeitscharakteristik, welcher mit einem Smartphone verbunden ist. Dort wird neben der Bestrahlungsstärke auch die zulässige Aufenthaltsdauer numerisch, graphisch und akustisch angezeigt. Weil für verschiedene Normen bzw. Strahlungsquellen spezifische Sensoren verwendet werden müssen, stellt das System sicher, dass der momentan angeschlossene Sensor zur Beurteilung der Strahlung nach der gewählten Norm geeignet ist. Dadurch werden der Aufwand und die Fehleranfälligkeit bei einer Gefahrenbewertung deutlich verringert und die Verwendung im Alltagsbetrieb gefördert.