X-ray and γ-ray detectors based on GaAs epitaxial structures

The growth of GaAs epitaxial structures for X- and gamma-ray detectors and the device characteristics have been investigated. Conditions of reproducible LPE growth of GaAs layers more than 100 mum thick on substrates of 40 mum diameter have been established. Complex doping with tin and deep Cr-acceptor have been studied for the liquid-phase epitaxial growth in a wide temperature range. A method has been developed for GaAs:Sn,Cr layer growth with the resistivity in the range (10(7)-10(9))Omega cm and with thickness up to 550 mum. Detector p-i-n structures have been fabricated on the base of high-resistivity GaAs layers. The electric field distribution and current flow mechanisms in the diodes have been studied. Diodes have been fabricated with a dark current density of 1 x 10(-7) A/cm(2) at a reverse bias voltage of 100 V. Alpha particle and gamma-ray spectra of the detectors have been measured. An X-ray image has been obtained with a strip detector based on LPE layers. (C) 2004 Elsevier B.V. All rights reserved.