IMPROVEMENT OF THE CRYSTALLINITY OF CDTE EPITAXIAL FILM GROWN ON SI SUBSTRATES BY MOLECULAR-BEAM EPITAXY USING THE 2-STEP GROWTH METHOD

Molecular beam epitaxy growth of CdTe epitaxial layers on Si (100) sub strates using the two-step growth method was performed to produce high -quality CdTe thin layers. The reflection high-energy electron diffrac tion patterns were streaky with clear Kikuchi lines, which is direct e vidence for layer-by-layer two-dimensional growth of CdTe on Si. From the X-ray diffraction analysis, the grown layer was found to be a CdTe (111) epitaxial film, regardless of the film thickness. Photoluminesc ence (PL) measurements at 12 K showed that the defect density of the C dTe film grown on Si using two-step growth decreased in comparison wit h that grown using direct growth. The bound exciton appearing in the P L measurements shifted to the low energy side as the thickness of the CdTe increased. When the CdTe thickness increased from 1 to 1.8 mu m, the peak position of the bound exciton shifted by 7.2 meV, and the str ess obtained from the exciton peak shift was -12.405 kbar. These resul ts indicate that high quality CdTe films grown by two-step growth hold promise for applications as buffer layers for the subsequent growth o f HgxCd1-xTe.