Response of semi-insulating 100μm thick GaAs detector for α-particles, γ-rays and X-rays

The 100μm thick, transmission, fully depleted GaAs Schottky barrier detector fabricated from LEC bulk GaAs crystals has been tested. The basic structure of the detector consists of a Cr/Au Schottky contact and an Au/Ge/Ni/Au alloyed ohmic contact. Pulse height spectra for α-particles resulting from irradiation with triple source 239Pu, 241Am, 244Cm, with energies 5.155, 5.486, 5.805 MeV were acquired. The energy resolution for these energies was better than 10 keV (1.8%). Using 241Am 5.486 MeV α-particles a charge collection efficiency (CCE) of about 94% was obtained at 570 V bias potential. The spectra of low-energy γ-rays 59.5 keV and X-rays with average energy 16.2 keV from 241Am source measured at room temperature are presented. An energy resolution of about 6.1 keV (10.3%) FWHM at 59.5 keV was obtained.