MULTISTEP FORMATION AND LATERAL VARIATION IN THE IN COMPOSITION IN INGAAS LAYERS GROWN BY METALORGANIC VAPOR-PHASE EPITAXY ON (001)VICINAL GAAS SUBSTRATES

In this paper, we investigate the substrate misorientation effect on I n0.2Ga0.8As/GaAs strained quantum wells grown on vicinal GaAs substrat es by metalorganic vapor phase epitaxy (MOVPE). Using cross-sectional transmission electron microscopy (TEM), stepbunching in an InGaAs laye r is observed. In addition, based on energy-dispersive X-ray (EDX) ana lysis, we report for the first time lateral variations in the In compo sition in an InGaAs layer grown on a vicinal substrate. It is found th at this variation in In composition and variations in the thickness ca use photoluminescence (PL) spectrum broadening. The dependence of PL p roperties on the growth conditions and on surface misorientation direc tion is also examined. Experimentals results are explained by discussi ng the diffusion length of Group III atoms and their tendency to attac h to step sites. TEM analysis confirms that the critical layer thickne ss of an InGaAs layer decreases on a vicinal substrate due to the form ation of stepbunches.