MICROSTRUCTURAL AND OPTICAL CHARACTERIZATION OF CDTE(211)B ZNTE/SI(211) GROWN BY MOLECULAR-BEAM EPITAXY/

CdTe layers have been grown by molecular beam epitaxy on 3 inch nomina l Si(211) under various conditions to study the effect of growth param eters on the structural quality. The microstructure of several samples was investigated by high resolution transmission electron microscopy (HRTEM). The orientation of the CdTe layers was affected strongly by t he ZnTe buffer deposition temperature. Both single domain CdTe(133)B a nd CdTe(211)B were obtained by selective growth of ZnTe buffer layers at different temperatures. We demonstrated that thin ZnTe buffer layer s (<2 nm) are sufficient to maintain the (211) orientation. CdTe depos ited at similar to 300 degrees C grows with its normal lattice paramet er from the onset of growth, demonstrating the effective strain accomm odation of the buffer layer. The low tilt angle (<1 degrees) between C dTe[211] and Si[211] indicates that high miscut Si(211) substrates are unnecessary. From low temperature photoluminescence, it is shown that Cd-substituted Li is the main residual impurity in the CdTe layer. In addition, deep emission bands are attributed to the presence of As-Te and Ag-Cd accepters. There is no evidence that copper plays a role in the impurity contamination of the samples.