Polarization Effects in the Photoluminescence of AlGaN and AlInGaN Based Quantum Well Structures

Abstract

AbstractWe have analyzed photoluminescence (PL) dynamics of GaN/AlGaN and AlInGaN/AlInGaN multiple quantum wells (MQWs) with different well and barrier widths. The quantum structures were grown by conventional metalorganic chemical vapor deposition and novel pulsed atomic layer epitaxy. In both types of MQWs a blueshift followed by a redshift of the PL peak position were observed with increasing excitation power, which we attributed to the screening of built-in electric fields and band gap renormalization, respectively. In bulk AlInGaN material or in MQWs with thin well widths the blueshift was not observed. This means that the incorporation of In into AlInGaN material in the amount required to fabricate smooth layers with strong emission at 330-350 nm does not create significant concentration of band-tail states. We have also evaluated the internal field in the MQW structures by comparing the experimental PL data to the simulations based on triangular quantum well model resulting from the polarization fields.