Rapid thermal annealing effects in CdTe (111) thin films grown on Si (100) substrates by molecular beam epitaxy

Photoluminescence (PL) measurements have been carried out to investigate rapid thermal annealing (RTA) effects in CdTe(111) epilayers grown on Si(100) by molecular beam epitaxy. The full width at half maximum (FWHM) of the bound exciton peak of the PL spectrum for the as-grown CdTe layer was 20 meV. When RTA was performed at 400 degrees C, the bound exciton peak was resolved into two bound exciton peaks due to neutral accepters (A degrees, X) and to neutral donors (D degrees, X) and one free exciton peak; the FWHM of the (A degrees, X) peak was as small as 3.7 meV. When RTA was carried out at 600 degrees C, the relative intensity ratio between the luminescences related to the defects and (A degrees, X) in the as-grown and the annealed CdTe layers decreased by a factor of 15. The activation energy of the (A degrees, X) peak as obtained from temperature-dependent PL measurements was 18.7 meV. The bound exciton peak for the CdTe, which was rapidly thermally annealed at 400 degrees C, shifted by 7.5 meV in comparison with that for the CdTe bulk, and the strain obtained from the PL peak shift was -0.0286. These results indicate that the crystallinity of the CdTe epilayers grown on Si is improved by RTA and that the RTA CdTe films grown on Si can be used for applications as buffer layers for the growth of HgxCd1-xTe.