GaAs High Breakdown Voltage Front and Back Side Processed Schottky Detectors for X-Ray Detection

Abstract : We have studied the current voltage and X-ray detection using front and back side processed, unintentionally doped bulk gallium-arsenic (GaAs) Schottky detectors and determined that GaAs detectors with a large enough thickness and low enough doping could be used for X-ray imaging, especially for medical applications. In this study, GaAs Schottky detectors were fabricated using front and back side photolithographic processing using Ti/Au for Schottky and Ge/Au/Ni/Au for ohmic contacts. A number of 2 2 mm detectors were tested. The breakdown voltage reached 600 800 V in semi-insulated (SI) GaAs Schottky front and back side processed detectors. For these detectors, the dark current was found to be between 2 90 nA. These detectors were also characterized with 150 keV, 3mA X-ray radiation and they responded well, showing more than a hundred fold increase in photocurrent due to production of electron hole pairs by the ionization processes. The processing of the detectors and the current-voltage (I-V) and X-ray characterizations are presented in this report.