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Proceedings Paper

Investigation of the current-voltage characteristics, the electric field distribution and the charge collection efficiency in x-ray sensors based on chromium compensated gallium arsenide
Author(s): A. Tyazhev; V. Novikov; O. Tolbanov; A. Zarubin; M. Fiederle; E. Hamann
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Paper Abstract

In this work we present the results of experimental study of the current-voltage characteristics, the electric field distribution and the charge collection efficiency in X-ray sensors based on high resistivity, chromium compensated gallium arsenide (HR GaAs). The experimental samples were 0.1-0.25 cm2 pad sensors with the sensitive layer thickness in the range of 250-1000 μm. It has been shown that the current-voltage characteristics in the range 0.02 – 1 V are determined by the high-resistance sensor bulk. A physical model of the nonequilibrium charge carrier transport has been suggested to estimate the Schottky barrier height in the contact of “metal-semiconductor” and the sensor material resistivity. It has been established that the sensor resistivity reaches 1.5 GOhm⋅cm at room temperature, with the Schottky barrier height constituting 0.80 – 0.82 eV. The electric field distribution was investigated using the Pockels effect at a wavelength of 920 nm. It has been found experimentally that in HR GaAs sensors the electric field distribution is much more homogeneous compared to the sensors based on SI GaAs: EL2. It has been shown that the temporal fluctuations of the electric field are absent in HR GaAs sensors. Analysis of the charge collection efficiency as a function of bias has demonstrated, that in the HR GaAs material the values of the mobility-lifetime product of the nonequilibrium charge carriers are in the order of 10-4 cm2/V and 3⋅10-7 cm2/V for electrons and holes, respectively.

Paper Details

Date Published: 5 September 2014
PDF: 12 pages
Proc. SPIE 9213, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XVI, 92130G (5 September 2014); doi: 10.1117/12.2061302
Show Author Affiliations
A. Tyazhev, Tomsk State Univ. (Russian Federation)
V. Novikov, Tomsk State Univ. (Russian Federation)
O. Tolbanov, Tomsk State Univ. (Russian Federation)
A. Zarubin, Tomsk State Univ. (Russian Federation)
M. Fiederle, Freiburger Materialforschungszentrum (Germany)
Karlsruher Institut für Technologie (Germany)
E. Hamann, Karlsruher Institut für Technologie (Germany)


Published in SPIE Proceedings Vol. 9213:
Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XVI
Arnold Burger; Larry Franks; Ralph B. James; Michael Fiederle, Editor(s)

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