The impurity-free vacancy diffusion behavior of In0.86Ga0.14As0.64P0.36/ In0.88Ga0.12As0.25P0.75 multiple quantum well structures, using dielectric films as a capping layer, was reported. The effects of SiOx and SiNx films deposited using various SiH4 flow rates on the impurity-free vacancy diffusion were investigated by photoluminescence measurements and ellipsometric analysis. The properties of dielectric capping layer played a key role in the intermixing of this multiple quantum well structure, indicating that the increased porosity of SiOx and SiNx layers enhanced the band-gap energy shift of multiple quantum wells. A significant blue shift of 173nm (106meV) for the sample capped with a relatively more porous SiNx, which was deposited using 20sccm SiH4, was obtained after annealing (850C, 30s). The mechanism was analyzed by using transmission electron microscopy and energy dispersive X-ray spectroscopy. It was believed that the enhanced blue shift was ascribed to the dominant interdiffusion of group V atoms because the compositions of group III atoms were kept almost identical in the wells/barriers.

Impurity-Free Vacancy Diffusion of InGaAsP/InGaAsP Multiple Quantum Well Structures Using SiH4-Dependent Dielectric Cappings. J.S.Yu, Y.T.Lee: Japanese Journal of Applied Physics, 2007, 46[10A], 6509-13