Photoinhibition of the quantum confined Stark effect in piezoelectric multiple quantum wells.

Abstract

We show that photoinduced space-charge buildup in piezoelectric [111]-oriented multiple quantum wells (MQW's), with average electric fields opposing the field in the barriers, inhibits the shifting of optical transitions by externally applied electric fields. This effect is due to the screening of the average electric field as photogenerated electrons and holes drift by this average field towards opposite locations in the MQW region. The resulting dipole flattens the envelope potential and hence precludes the change of energy levels with variations of external field. This behavior has been observed in different device configurations employing ${\mathrm{In}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Ga}}_{\mathit{x}}$As/GaAs MQW embedded in a p-i-n diode by low-temperature photoluminescence (PL) and photocapacitance spectroscopies under different bias conditions. In addition to these ``self-locked'' transitions, we also observe other peaks in the PL spectra that result from the charge accumulation effect and that are qualitatively explained using Hartree calculations. \textcopyright{} 1996 The American Physical Society.