Self-aligned molecular beam epitaxy of CdZnTe for IR focal plane arrays

The crystallographic orientation of Cd1-xZnxTe (x approximately equals 0.045) grown by molecular beam epitaxy (MBE) on a clean (planar) (100) GaAs surface can be controlled by the proper choice of the GaAs surface stoichiometry. An As-stabilized surface initiates (100) oriented growth, while the Ga-stabilized surface yields (111) oriented growth. Cd1-xZnxTe (x approximately equals 0.045) MBE layers grown in recesses of shadow masked patterned (100) GaAs substrates were found to be in the (100) orientation regardless of whether precursor surfaces were stabilized with Ga or As. The epitaxial layer's orientation and optical properties were determined by backscattered electron channeling and low temperature photoluminescence measurements, respectively. CdZnTe layers grown in recesses showed improved optical features as compared to the layers grown on planar substrates.