Influence of net strain, strain type, and temperature on the critical thickness of In(Ga)AsP-strained multi quantum wells

We examined the critical thickness of strained multi quantum wells (MQWs) c onsisting of InAsP/ InGaAsP and InGaAsP/InGaAsP. More than 50 MQWs with dif ferent total thicknesses, well strain, and well thicknesses were prepared b y metalorganic molecular beam epitaxy (MQMBE) or metalorganic vapor phase e pitaxy (MOVPE) to study the influence of net strain, strain type, and tempe rature on critical thickness. The microscopic photoluminescence method was used mainly to observe misfit dislocations in the MQWs. Three kinds of net strain-critical thickness curves were experimentally determined, i.e., the curves for compressive as well as tensile strained MQWs grown by MOMBE and that for compressive strained MQWs grown by MOVPE. We found that the above three curves coincide with each other and differ greatly from the Matthews' [J. W. Matthews and A. E. Blakeslee, J. Cryst. Growth 27, 118 (1974)] theo retical curve in a low-net strain range of less than 0.5%. (C) 1998 America n Institute of Physics. [S0021-8979(98)03121-1].