X-RAY-DETECTION USING BULK GAAS

Bulk GaAs has been investigated as a material for X-ray detection nomi nally in the 10-100 keV band using Schottky barrier detectors. The dev ices which were manufactured were investigated with respect to leakage current, charge collection efficiency and X-ray spectral resolution. A leakage current of 7 nA mm-2 at 20-degrees-C was measured and was no t attributable to surface leakage. The X-ray charge collection efficie ncy was variable but was as high as 70%, due to defects in the bulk ma terial and was a strong function of detector thickness and applied bia s. The imperfect CCE results in degraded spectral resolution, however the work indicates that this type of detector can perform moderate spe ctroscopy for X-rays of energy > 14 keV, with a measured FWHM of 4.5 k eV at 60 keV and 5.5 keV at 122 keV.