Effect of doping in barrier on photo-reflectance spectra of InGaAs/InAlAs MQWs; donor-states and QW eigen-states

We have observed the ground and the first-higher impurity states associated with InGaAs conduction subbands in photo-reflectance spectra of InGaAs/InAlAs multi-quantum well (MQW), using a series of differently doped specimens. Donors were homogeneously doped within InAlAs barriers. A series of three interband transitions between conduction and valence subbands were identified by comparing our previous photocurrent spectroscopy and by fitting the difference of eigen-energies using Kane's nonparabolic band theory.