INTERDIFFUSION OF IN, TE AT THE INTERFACE OF MOLECULAR-BEAM EPITAXIAL GROWN CDTE/INSB HETEROSTRUCTURES

One of the serious problems for the formation of good quality interfaces of InSb/CdTe by molecular beam epitaxy (MBE) growth is the precipitation of In-Te related compounds at the interface resulting from interdiffusion of In and Te. We have tried to insert an alpha-Sn layer at the interface to prevent the interdiffusion and the propagation of planar defects which may enhance the diffusion. In this study, proof that an alpha-Sn layer grown at 150 degrees C prevents the interdiffusion is given by comparing Raman spectroscopy data on CdTe/alpha-Sn/InSb with those on alpha-Sn/CdTe/InSb and CdTe/InSb structures. When the alpha-Sn layer was grown at 220 degrees C, the Raman data showed that the prevention of interdiffusion became imperfect, although, the in-situ observed reflection high energy electron diffraction (RHEED) pattern indicated a high quality alpha-Sn layer. An insertion of one monolayer of Cd at the interface of alpha-Sn/CdTe improved the quality of the alpha-Sn layer and an over pressure of Cd during the growth of CdTe improved the quality of the CdTe caplayer.