Characterizing electric fields in (111)B InGaAs quantum wells using electric field modulated photoluminescence and reflectance techniques

Abstract

We have performed a series of electroreflectance, photoluminescence, and electric-field-modulated photoluminescence experiments to characterize the strain-induced electric fields in (111)B InGaAs/AlGaAs quantum well p-i-n diode structures. A 180° phase change in the lineshapes of electroreflectance spectra of these samples determines when the quantum well is biased to flatband. Using this bias and a depletion model for the diode, the polarization field in the quantum well can be determined. Contrary to expectations, this polarization field increases significantly with increasing temperature. In addition, at fixed temperature, the quantum well transition energies red-shift with increasing excitation intensity when excited by photons of energy higher than the lowest quantum well transition but lower than the AlGaAs diode's bandgap. When excited with photons of energy greater than the AlGaAs bandgap, the transition energy first red shifts then blue shifts with increasing excitation intensity.