DEVELOPMENT OF BULK GAAS ROOM-TEMPERATURE RADIATION DETECTORS

GaAs is a wide band gap semiconductor with potential use as a room temperature radiation detector. Various configurations of Schottky diode detectors were fabricated with bulk crystals of liquid encapsulated Czochralski (LEC) semi-insulating undoped GaAs material. Basic detector construction utilized one Ti/Au Schottky contact and one Au/Ge/Ni alloyed ohmic contact. Pulsed X-ray analysis indicated pulse decay times dependent on bias voltage. Pulse height analysis disclosed non-uniform electric field distributions across the detectors tentatively explained as a consequence of native deep level donors (EL2) in the crystal. Pulse height spectra measured from an Am-241 alpha particle source at room temperature resulted in resolution ranging from 2.2% to 3.1% at FWHM for several detectors with a typical resolution of 2.5%. Low energy gamma rays measured under room temperature operating conditions resulted in observed full energy peaks of 60 keV and 122 keV photons with measured FWHM's of 22 keV and 40 keV, respectively.