PHOTOLUMINESCENCE PROPERTIES OF MOVPE GROWN ZNTE LAYERS ON (100) GAAS AND (100) GASB

Single-crystalline ZnTe layers have been successfully grown on (100) oriented GaAs and GaSb substrates by atmospheric-pressure MOVPE. The surfaces are mirrorlike and show a microstructure smaller than 1 μm when grown at temperatures between 330 and 370°C. These low growth temperatures have been achieved using diethylzinc and diisopropyltelluride as metalorganic precursors. Temperature-dependent photoluminescence (PL) measurements have been carried out to identify incorporated impurities and to optimize the growth conditions. Several luminescence bands can be assigned to shallow traps formed by specific impurities as Ga (binding energy EB = 18.6 meV), As (EB = 78.5 meV) and possibly Si. Best growth results have been achieved at a growth temperature of 350°C and a ratio R (DiPTe/DEZn) = 2.0. In ZnTe layers thus obtained, free exciton luminescence was observed at 2.3795 eV (Mj = ± 3 2 valence band) and 2.3806 eV (Mj = ± 1 2) at 10 K. PL spectra of ZnTe grown on GaSb at 350°C and R = 2.0 show the Si line but not the As line; instead, a line corresponding to EB = 73.8 meV was tentatively assigned to Sb. Likewise the optical quality had strongly increased, due to the much smaller lattice mismatch of 0.1% between ZnTe and GaSb compared with 8% for GaAs. Also the free exciton Mj = ± 1 2 transition (2.3808 eV at 10 K) is clearly separated from the one with Mj = ± 3 2 (2.3794 ev) by an energy of 1.4 meV. © 1989.