The Polarity Effect on the Photoelectrochemical Properties of Ga- and N-Face Free-Standing GaN Substrate

Abstract

The band-edge potential and photocurrent density of N-face GaN were experimentally determined to be more negative and greater than those of Ga-face GaN, respectively, in this photoelectrochemical experiment. These results indicate that the N-face GaN could generate much more hydrogen than Ga-face GaN. Although the time dependence of the photocurrent density of N-face GaN was almost constant, that of Ga-face GaN stabilized only after 260 min of reaction time. From these results, we conclude that N-face GaN, which has a more negative band-edge potential and a more stable photocurrent density, could be suitable for higher-photocurrent generation than Ga-face GaN.

Highly Stable Bulk GaN Photoanode Grown by Hydride Vapor-Phase Epitaxy for Photoelectrochemical Water Splitting

“…This indicates that bulk GaN can split water without bias under light irradiation, regardless of plane polarity. 20 The difference in the flatband potentials of polar and semipolar GaN could be explained by the different arrangement of Ga atom and N atom in the terminated surface of the polar and semipolar GaN.…”

“…We chose an N-face polar GaN as the polar GaN epilayer because we obtained better results for an N-face polar GaN in a previous study. 15…”

Photoelectrochemical etching of epitaxial InGaN thin films: self-limited kinetics and nanostructuring

“…Because the MOVPE-grown III-nitride material is oriented with the N-face downward, this image provides atomic resolution evidence of the preferential PEC etching of N-faces over the Ga-faces [11,12]. After 15 minutes, the lateral etch-distance increases to ~ 30 to 40 nm (Figure 8d).…”

“…Photoelectrochemical (PEC) etching has recently shown promising as an alternative wet process for gallium nitride and its alloys [11][12][13][14]. Under illumination of ultraviolet light the etch rate is greatly enhanced, up to ~ 1 µm per minute.…”