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Semiconductor Physics, Quantum Electronics & Optoelectronics. 2006. V. 9, N 2. P. 092-094.
The influence of Cr concentration
on time resolution of GaAs detectors
1V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine,
45, prospect Nauky, 03028 Kyiv, Ukraine
Phone: +380 (44) 525-64-77, +380 (44) 525-18-75, +380 (44) 525-59-39;
e-mail: lfedor@isp.kiev.ua, ny@isp.kiev.ua, slv@isp.kiev.ua
Abstract. Investigated in this work were the influence of Cr dopant concentration and
technological conditions of doping on photoconductivity (PhC) kinetics, dependence of
PhC signal magnitude on voltage applied as well as the dynamic range of a photodetector
based on semi-insulating GaAs:Cr. PhC relaxation was measured using a broadband
system of registration in the picosecond pulse range, which is based on the oscillograph
C7-19, CCD camera and personal computer. Mechanisms of recombination that
influence on fast and slow components of the PhC signal were studied. The shortest time
of PhC relaxation τ ~ 2 . 10
−10 s was observed in GaAs:Cr samples for the chromium
dopant concentration N Cr ~ 3 . 10 17 cm
−3 . We have found a linear increase of the fast
component of PhC with the intensity of excitation as well as a weak dependence at small
levels and saturation at the high ones of excitation for the PhC slow component.
Keywords: GaAs, fast detector, picosecond YAG-laser, X-, γ-radiation, photo-conductivity.
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