EFFECT OF SUBSTRATE AUTODOPING ON MOVPE-GROWN ZNSXSE1-X AND ZNSE - ANALYSIS BY PHOTOLUMINESCENCE (PL) AND SECONDARY ION MASS-SPECTROMETRY (SIMS)

The effect of substrate outdiffusion on the optical properties and compositional integrity of high quality ZnSe and ZnS//xSe//1// minus //x (0 less than x less than 1) grown by atmospheric pressure metalorganic vapour phase epitaxy (MOVPE) was investigated by low temperature photoluminescence (PL) and secondary ion mass spectrometry (SIMS) depth profiling analyses. Substrate outdiffusion was found to occur in the ZnSe/GaAs and lattice mismatched ZnS//xSe//1// minus //x(0 less than x less than 1)/GaAs systems but not appreciably in the ZnSe/Ge and lattice matched ZnS//xSe//1// minus //x (x equals 0. 06)/GaAs as indicated by diffuse and abrupt compositional SIMS depth profiles respectively. Low temperature PL measurements indicated changes in the main excitonic recombination transitions for ZnSe/GaAs. In particular the emphasis changes from the I//2**G**a donor bound exciton emission for thin layers to the I//x native donor bound exciton emission for thicker layers. The I//2**G**a donor bound exciton peak is also dominant in the lattice mismatched ZnS//xSe//1// minus //x (0 less than x less than 1).