Heteroepitaxy of II-VI and IV-VI semiconductors on Si substrates

Abstract

We report on our progress of Il-VI and IV-VI compound semiconductor heteroepitaxy on Si(1 1 1) and (100) substrates by MBE. A stacked buffer layer of CaF2 SrF2 and BaF2 serves to overcome the large lattice and thermal expansion mismatches between the different materials. Undoped and Sb-doped epitaxial CdTe on Si(100) layers exhibit superior surface morphologies and photoluminescence spectra when illuminated with an Ar-laser during growth however dopant activation is much less pronounced as compared to work performed on homoepitaxial CdTe layers on CdTe(100) substrates. 3 im thick PbTe and PbiSnSe layers deposited on fluoride covered Si exhibit x-ray line widths as low as 150-200 arc sec and their mechanical thermal mismatch strain is fully relaxed at room temperature. Up to now growth of epitaxial Il-VT and IV-VI layers of reasonable. quality directly on Sisubstrates using any technique has not been reported. This is because of the high lattice and thermal expansion mismatch between the different materials as well as because of chemical compatibility. Growth of good quality layers has been reported only with an appropriate buffer layer. We have found that group ha fluorides namely CaF2 SrF2 and BaF2 form such a buffer and have been able to grow for the first time high quality epitaxial Il-VI materials (CdTe [1 as well as IV-VI materials (PbSe [3] PbS [4] PbTe Pbi SnSe [5-7] and Pb1EuSe [8]) on Si-substrates. IRsensors were