The critical thickness of strained multi quantum-wells which consisted of InAsP/InGaAsP and InGaAsP/InGaAsP was examined. Some 50 multi quantum-wells, with various total thicknesses, well strain, and well thickness, were prepared by metalorganic molecular-beam epitaxy or metalorganic vapor-phase epitaxy. The microscopic photoluminescence method was used to observe misfit dislocations in the multi quantum-wells. Three types of net-strain versus critical-thickness curve were detected experimentally. These were the curves for compressively- and tensile-strained multi quantum-wells grown by metalorganic molecular-beam epitaxy and that for compressively strained multi quantum-wells grown by metalorganic vapor-phase epitaxy. It was found that the 3 curves coincided with each other, but differed greatly from Matthews' theoretical curve at net strains below 0.5%.

Influence of net strain, strain type, and temperature on the critical thickness of In(Ga)AsP-strained multi quantum wells M.Ogasawara, H.Sugiura, M.Mitsuhara, M.Yamamoto, M.Nakao: Journal of Applied Physics, 1998, 84[9], 4775-80