GaN for x-ray detection

The potential of GaN based materials for x-ray detection is investigated. The absorption coefficient in GaN is measured as a function of photon energy between 6 and 40keV. Metal-semiconductor-metal photodetectors are fabricated and characterized. The response dependence on bias, the temporal dynamics, and the response dependence on detector geometry all together point toward a mixing of photovoltaic and photoconductive effects. Thanks to a large photoconductive gain, the detector has a decent responsivity at the expense of a large response time.