MOMBE growth of highly tensile-strained InGaAsP MQWs and their applications to 1.3-μm wavelength low threshold current lasers

Abstract

We have studied metalorganic molecular beam epitaxy (MOMBE) of InGaAsP multi-quantum wells (MQWs) with 0.5-1.8% tensile-strained well layers. The MQW photoluminescence intensity depends significantly on the barrier layer strain to compensate well layer strain. Optimizing the strain compensation conditions, i.e., keeping the net strain less than 0.3%, makes it possible to grow high optical quality MQWs with 1.8%-strained, 10-well layers. A critical thickness-net strain (t c -e*) curve for the tensile-strained MQWs has been experimentally determined by analyzing more than 50 samples with various strains and total thicknesses. The t c -e* curve fairly agrees with the one calculated by the Matthews formula for more 0.5% net strain, but the t c values are much higher than the expected ones below that range. For 6-well MQW lasers, the threshold current densities, J th 's, decrease with increasing tensile strain; the minimum J th obtained is 0.6 kA/cm 2 at 1.3% strain.