Performance of SI LEC GaAs detectors at 20°C and −30°C for X- and γ-ray spectroscopy

We report on the performance and limitations of a 7 mm2, 100 μm thick SI LEC GaAs detector, operated in overdepleted conditions with applied bias of 400 V at 20°C and −30°C, in detecting X- and γ-rays. At 20°C performance is limited to a charge collection efficiency of 92% and to an energy resolution of about 16.8 keV FWHM on the 59.5 keV line of 241Am. At −30°C the charge collection efficiency is 85% and a resolution in between 1.8 and 2.2 keV FWHM in the photon energy range 8–60 keV has been achieved. The latest data represent to our knowledge the best ones yet reported for GaAs LEC detectors.