Photoreflectance of GaAs/GaAlAs multiple quantum wells: Topographical variations in barrier height and well width

Abstract

Using photoreflectance at room temperature we have evaluated the topographical variations in quantum level transitions of a GaAs/GaAlAs multiple quantum well (220 Å/150 Å) due to changes in barrier height and quantum well width. The spatial resolution of the measurement was about 100 μm. A key feature of our analysis is the ability to fit the electromodulation spectra by a third-derivative functional form line shape factor. We can detect barrier height changes of several millielectron volts and variations in well width as small as 2 Å.