Hg 1−xCd xTe epitaxial layers grown by low mercury partial pressure metalorganic chemical vapor deposition and extended defect characterization.

Abstract

There are two growth methods in Hg 1−xCd x Te metalorganic chemical vapor deposition (MOCVD) growth, namely direct alloy growth (DAG) and the interdiffused multilayer process (IMP). HgCdTe layers have been grown by both methods onto CdZnTe (111)B substrates and their structural and electrical properties were investigated. The composition fluctuated significantly along the growth direction for DAG. On the other hand, there were many misfit dislocations in the IMP layers, presumably generated by the lattice mismatch between the HgTe and CdTe layers. Here we have investigated DAG HgCdTe growth under low mercury partial pressure in order to improve depth compositional uniformity, misfit dislocation density and the lamella twin density. This low mercury partial pressure growth gave mercury transport limited growth for HgTe as in the conventional growth of III–V compounds by MOCVD. The Hg 0.8Cd0.2Te layers grown by the new method (p-type 3.4x10 15 cm -3 for carrier concentration, 520 cm 2 V·s for mobility in as-grown samples) were found to be improved with respect to depth compositional uniformity and dislocation density.