Chemical doping of HgCdTe by molecular‐beam epitaxy

Chemical doping of HgCdTe is an important issue in II–VI compound semiconductors. In this paper, we will report on the molecular‐beam epitaxy (MBE) growth and characterization of n‐ and p‐type HgCdTe. We have grown n‐ and p‐type layers of HgCdTe with indium and arsenic as the dopants using MBE at 170 °C–180° C without photo or ion excitation. The doped layers, which range from 10¹⁵ cm⁻³ to 10¹⁸ cm⁻³ have been characterized by a variety of techniques including infrared IR transmission, Hall measurement, scanning electron microscopy, minority carrier lifetime, and secondary ion mass spectroscopy. The results indicate that n‐type alloy layers are easier to form than p type because of the efficient incorporation of indium in the mercury (or cadmium) sublattice. Memory effects of indium were not observed. We have also demonstrated that our p‐type layers remain p type after mercury anneal indicating that they are extrinsically doped. The breakthrough in chemical doping of HgCdTe has enabled us to grow several double layer heterojunction structures. Several diodes have been fabricated and their electrical and optical characteristics are discussed.