Improved breakdown voltage in molecular beam epitaxy HgCdTe heterostructures

Abstract

We present recent progress in the development of metal–insulator–semiconductor (MIS) heterostructure detectors grown by molecular beam epitaxy (MBE); these heterostructure films should significantly improve the available well capacity for MIS long wavelength infrared (LWIR) detectors. Recent MBE grown HgCdTe(112)Te heterostructures show a 4× increase in available charge capacity and a 2× decrease in net donor density relative to our MBE HgCdTe(001) layers. To obtain full advantage of the MIS heterostructure however, another 2.5× increase in the MWIR breakdown field (0.8–2.0 V/μm) and a 2× decrease in the MWIR donor density (1×1015–5×1014cm−3) is necessary. Since the MWIR breakdown field does not appear to be limited by compositional micro-inhomogeneities or by compound twin defects in the MBE HgCdTe layers, we suspect either dopant micro-inhomogeneities or native point defects are responsible for the significant tunnel currents measured in our MWIR MBE HgCdTe.