Hg 1−x Cd x I 2 /CdTe heterostructures for nuclear radiation detectors: Effect of epitaxial growth on substrate properties

Abstract

We demonstrate the possibility to fabricate nuclear radiation detectors operating at room temperature from CdTe substrates affected by the vapor phase epitaxy (VPE) growth of Hg1−xCdxI2 layers. The VPE layers with the thickness 10–30 μm were grown using an α-HgI2 polycrystalline source at 220 °C and time in the range of 30–100 h. The as-grown heterostructures were chemically etched to remove the epilayers, and Au–CdTe–Au detectors were made. The substrates were characterized by synchrotron x-ray topography before and after the VPE growth, and the current–voltage (I–V) and spectroscopic measurements of the detectors were carried out. The effect of the VPE growth on the substrates and detectors has been studied and on the basis of this it has been possible to fabricate γ-ray detectors with Ohmic I–V characteristic and good spectral response.