The X-ray response of InP

We present the results of X-ray measurements on a prototype InP detector. The device was fabricated from Fe-doped bulk material of size 3×3×0.18 mm3. X-ray measurements have been carried out using a number of radioactive and fluorescent target sources. The detector energy response function was found to be linear over the energy range 5.9–88 keV with an average rms non-linearity of 0.7%, consistent with statistics. At a detector temperature of −60°C, the FWHM energy resolution under full-area illumination was 2.5 at 5.9 keV rising to 12 at 88 keV. Analysis of the energy resolution function indicates that poor charge transport presently limits the performance of InP detectors.