Transmission electron microscopy and X-ray diffractometry were used to study strain relaxation and the evolution of the dislocation structure in ZnSe epilayers that had been grown, by means of low-pressure organometallic vapor-phase epitaxy, onto the (001) surfaces of semi-insulating GaAs. Before ZnSe deposition, the substrate surface had been exposed to a flux of tertiarybutylarsine in order to produce an As-terminated surface. This surface treatment resulted in a low density of stacking faults. It was also noted that 60 misfit dislocations were observed at layer thicknesses of as little as 0.05. This observation agreed well with the theoretical critical value for misfit dislocation formation in this system, but was much lower than previously reported critical thicknesses. Differing mechanisms for misfit dislocation generation were observed at the various growth stages. The evolution of the dislocation structure was considered with regard to the morphology of the ZnSe layers.

S.Ruvimov, E.D.Bourret, J.Washburn, Z.Liliental-Weber: Applied Physics Letters, 1996, 68[3], 346-8