Hard X-ray detection with a gallium phosphide Schottky diode

We report on the detection of hard X-rays using a GaP Schottky diode at the HASYLAB synchrotron radiation research facility. Exposure to alpha particles from an 214Am source showed that the device was spectroscopic at room temperature with a FWHM energy resolution of 3.5% at 5.5 MeV. It was also found to be responsive to X-rays in the range 11–100 keV. Although individual energies are not spectrally resolved there is a proportionality of response to increasing X-ray energy. A two-dimensional scan of the sensitive area using a 30×30 μm2 30 keV pencil beam showed the spatial response of the detector to be uniform at the few percent level, consistent with statistics.