Photovoltaic X-ray detectors based on epitaxial GaAs structures

Abstract

A new type of the photovoltaic X-ray detector based on epitaxial p +-n-n′-n + GaAs structures is proposed, which provides for a high efficiency of charge carrier collection in a nonbiased operation regime at room temperature. The GaAs structures were grown by vapor phase epitaxy on heavily doped n +-GaAs substrates. The X-ray sensitivity range covers the effective energies from 8 to 120 keV. The maximum output signal in the short-circuit regime is 30 μA min/(Gy cm2). The detector response to γ-radiation from a 137Cs[660 keV] radioactive isotope was measured.