EFFECT OF THERMAL ANNEALING ON THE STRUCTURAL AND OPTICAL-PROPERTIES OF CDTE(111) GAAS(100) HETEROSTRUCTURES

Reflection high-energy electron diffraction (RHEED), double-crystal X- ray rocking curve (DCRC), and photoluminescence (PL) measurements were performed to investigate the effect of thermal annealing on the struc tural and the optical properties of CdTe (111) epilayers grown on GaAs (100) substrates by molecular beam epitaxy (MBE) at low temperature. The results of the RHEED patterns showed that the oxidized layer on th e GaAs substrate was removed in a Te atmosphere, and that the 20-Angst rom CdTe layer was grown by three-dimensional process. When the rapid thermal annealing (RTA) was performed at 500 degrees C for 14 s, the F WHM of the DCRC for the CdTe layer had the smallest value. After the R TA process, the luminescence intensity of the exciton remarkably incre ased, and the peak at 1.476 eV was dominant. As the RTA temperature in creased, the luminescence intensity of the exciton peak related to neu tral acceptors (A degrees, X) increased. The temperature dependence of the spectra showed that the (A degrees, X) peak originated from the r ecombination of the excitons bound in high-density defects. The excita tion power intensity dependence of the PL spectra should that the peak s of the transitions due to donor-acceptor pairs shifted to larger ene rgies. These results indicate that the structural and the optical prop erties of the CdTe epilayers grown on GaAs (100) are improved by RTA, and that the RTA process is very useful for the growth of HgxCd1-xTe o n CdTe/GaAs heterostructures. (C) 1997 Elsevier Science S.A.