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2012 – Highly reliable Silicon Carbide photodiodes for visible-blind ultraviolet detector applications

von

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).

Abstract
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.

2011 – Characterisation of new optical diffusers used in high irradiance UV radiometers

von

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.

Abstract
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.

2011 – Characterisation of SiC photodiodes for high irradiance UV radiometers

von

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.

Abstract
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.

2009 – Electronic and photoelectrical properties of semiconducting titanium dioxide layers

von

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.

2005 – Electrical transport in passivated Pt/TiO2/Ti Schottky diodes

von

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.