Photoreflectance spectroscopy of Si surface delta doping on GaAs (001)

Photoreflectance (PR) spectroscopy system is combined with molecular beam epitaxy (MBE) to accomplish in-situ PR measuring of the Si surface (delta) doping on GaAs (001) with different concentrations at different temperatures. The features observed on the high-energy side of the fundamental gap are attributed to transitions involving electronic subbands in the half V-shaped potential well. We find that the Si (delta) -doping-related spectral structure first shifts to high energy side with the doping concentration increasing, then almost stop shifting with the doping concentration higher than 2.4 X 1014 cm-2 when temperature increases, at certain doping concentration the Si (delta) - doping-related transition shifts toward low energy side. The dependence of the transition on doping concentration is well explained by using a simple theoretical model.