Experimental characterization of interface roughness in strained InGaAs/InP MQWs after a growth interruption sequence

The authors report on the interface roughness of a series of thin InGaAs/InP multiple quantum wells (MQWs) grown with interruption sequences performed at both the lower and the upper interfaces. They compare spectrometric data collected at 2°K with high-resolution transmission electron microscope images and show that the lower interface morphology (InP/InGaAs) originates only from the well known effect of P exchanging by As when first switching the gas species, but must take into account the effects of in-situ diffusion. Nothing similar should appear at the higher interface (InGaAs/InP) but a considerable amount of interface roughness is still present in HR-TEM images. It is shown that it originates from unperfected two-dimensional growth kinetics of InGaAs