Flat-band potentials of GaN and InGaN/GaN QWs by bias-dependent photoluminescence in electrolyte solution

Abstract Flat-band potentials of n-GaN and selectively doped n-In 0.17 Ga 0.83 N/GaN quantum wells (QWs) grown by metalorganic vapor phase epitaxy are determined by measuring the bias dependence of photoluminescence intensity in electrolyte solutions for different pHs. The In 0.17 Ga 0.83 N/GaN QWs with the absorption edge of 430 nm in the photocurrent spectrum, has a lower flat-band potential (−0.86 V vs. Ag–AgCl ) than that of n-GaN (−1.07 V), but the flat-band potential of QWs is still higher than the hydrogen generation potential (approximately −0.6 V) at pH 6.86. The difference in flat-band potentials observed between n-GaN and In 0.17 Ga 0.83 N/GaN QWs is smaller than the conduction band-offset estimated from the reported relationships by more than 0.1 V.