Thermal stability of (Zn,Cd)(Se,S) heterostructures grown on GaAs

We have analyzed the thermal stability of ZnSe-based single quantum well structures grown on a GaAs substrate by applying a rapid thermal annealing process. The photoluminescence intensity of the quantum well was used as a monitor for the thermal changes induced by the annealing process. X-ray diffractometry yields information about the crystal quality and the strain condition before and after the thermal treatment. As a main result, we found that the thermal stability of the quantum well photoluminescence signal critically depends on the thickness of the II-VI buffer layer, i.e., the distance between the active layer and the GaAs-II-VI heterointerface. For a buffer layer thickness of about 38 nm, the quantum well signal is totally quenched after a 1 min annealing step at 500 degrees C, while clear luminescence signals can be observed in samples with a 1 mu m buffer even for a 750 degrees C process. Additionally, by comparing CdZnSe/ZnSe and ZnSe/ZnSSe quantum wells, we found that the Cd-Zn interdiffusion seems to be more efficient than the S-Se interdiffusion. (C) 1996 American Institute of Physics.