Observation of compositional modulation in (111)A InGaAs quantum wells and the effect on optical properties

Abstract

We have studied the growth of InGaAs/GaAs multiple quantum wells (MQWs) on (111)A GaAs. Uniform thickness of (111)A quantum wells is observed by the cross-sectional transmission electron microscopy (TEM). Growth induced long-range In- and Ga-rich InxGa1-xAs/InyGa1-yAs superlattice in (111)A is also observed by cross-sectional TEM in the ternary InGaAs wells. In contrast, none of the above superstructure was observed by TEM on a side-by-side grown (100) oriented substrate. However, the photoluminescence (PL) linewidth is broadened by such compositional modulation. Low-temperature (15 K) photoluminescence showed a broad PL linewidth of 27.5 meV for In0.16Ga0.84As/GaAs MQWs grown on (111)A substrates at 520 degrees C. A decreased PL linewidth of 15.7 meV and a reduced compositional modulation in InGaAs wells can be achieved at a higher growth temperature of 560 degrees C. (C) 1996 American Institute of Physics.