Light-induced mobility enhancement in delta-doped GaAs/In0.26Ga0.74As/GaAs quantum wells grown by molecular beam epitaxy on GaAs(001)

Abstract

Persistent photoconductivity in 80 angstroms strained GaAs/In0.26Ga0.74As/GaAs quantum wells was investigated by measuring the Shubnikov de Haas and Hall effects at 4.2 K. The quantum wells were grown by molecular beam epitaxy at 480 °C and were delta-doped with Si either at the center, at the lower interface, or at the bottom barrier. Exposure to 654 nm red light leads to electrostatic bandbending, which converts the asymmetric quantum well to square-like and shifts the charge distribution away from the delta layer ionized impurities, improving the mobility. This bandbending effect is attributed to electron-hole pair generation and separation and/or deep states photoionization.