Strained CdZnTe/CdTe Superlattices As Threading Dislocation Filters in Lattice Mismatched MBE Growth of CdTe on GaSb

Abstract

In this work, multiple sets of CdZnTe/CdTe strained-layer superlattices have been used as dislocation filtering layers for reducing the threading dislocations and improving the material quality of CdTe buffer layers grown by molecular beam epitaxy (MBE) on GaSb (211)B substrates. By incorporating a CdZnTe/CdTe superlattice filtering structure, a significant improvement in material quality has been achieved, with a low etch pit density of ∼ 1 × 105 cm−2 demonstrated for CdTe grown on GaSb, which is two orders of magnitude lower than previously reported values for CdTe grown directly on lattice mismatched substrates, and is comparable to values for state-of-the-art CdTe grown on lattice matched CdZnTe substrates. The filtering efficiency for each set of dislocation filtering layers has been determined to be approximately 70%. This approach provides a promising pathway towards achieving hetero-epitaxy of high quality HgCdTe on large-area lattice-mismatched alternative substrates with a low dislocation density for the fabrication of next generation infrared detectors with features of lower cost and larger array format size.