Improve molecular beam epitaxy growth of HgCdTe on CdZnTe (211)B substrates using interfacial layers of HgTe/CdTe superlattices

HgTeCdTe superlattices (SLs) have been grown on CdZnTe (211)B substrates as interfacial layers to improve the reproducibility and material properties of epitaxial HgCdTe. The interfacial SL layer is found by transmission electron microscopy to be capable of smoothing out the substrate's surface roughness and to bend or block threading dislocations from propagating from the substrate into the functional HgCdTe epilayers. The best etch pit density values of 4× 104 cm-2 were achieved in long-wavelength infrared HgCdTe epilayers with such interfacial layers, while typical values were in the low 105 cm-2 range. The recombination mechanisms in such layers were dominated by radiative and Auger intrinsic recombination mechanisms, whereas the contributions from the Shockley-Read-Hall mechanism become negligible, which demonstrated that the use of the SL interfacial layers was beneficial for HgCdTe growth using molecular beam epitaxy or MBE.