Photoluminescence from surface GaN/AlGaN quantum wells: Effect of the surface states

TL;DR

This study investigates photoluminescence in GaN/AlGaN surface quantum wells at 85 K, revealing a redshift with decreasing width due to surface acceptor interactions, differing from conventional quantum well behavior.

Contribution

It demonstrates the influence of surface acceptors on PL spectra and identifies two types of acceptors affecting exciton recombination in surface quantum wells.

Findings

PL spectra show redshift with decreasing SQW width

Surface acceptors cause exciton coupling and recombination

Two types of surface acceptors were identified

Abstract

We report on photoluminescence (PL) measurements at 85 K for GaN/AlGaN surface quantum wells (SQW's) with a width in the range of 1.51-2.9 nm. The PL spectra show a redshift with decreasing SQW width, in contrast to the blueshift normally observed for conventional GaN QW's of the same width. The effect is attributed to a strong coupling of SQW confined exciton states with surface acceptors. The PL hence originates from the recombination of surface-acceptor-bound excitons. Two types of acceptors were identified.