Measuring valence band offsets in ReSe₂/(0001)GaN, ReSe₂/(11-22)GaN, and ReSe₂/(11-20)GaN heterostructures

Abstract Compared to conventional (0001)-oriented GaN-based devices, which suffer from performance-degrading polarization effects at the heterojunction interfaces, semipolar (11–22) GaN and nonpolar (11–20) GaN have demonstrated significant potential for reducing or eliminating these polarization effects, thus offering possibilities for enhancing device performance. Here, we have fabricated ReSe 2 /(0001) GaN, ReSe 2 /(11–22) GaN, and ReSe 2 /(11–20) GaN heterostructures to investigate the impact of different GaN crystal orientations on the band alignment of ReSe 2 /GaN heterostructures. Band alignments were characterized using x-ray photoelectron spectroscopy. The measured VBOs for the three ReSe 2 /GaN heterostructures (polar, semipolar, nonpolar) were determined to be 3.08 ± 0.15 eV, 2.62 ± 0.15 eV, and 2.24 ± 0.15 eV, respectively, while the calculated conduction band offsets were 1.51 ± 0.15 eV, 1.05 ± 0.15 eV, and 0.67 ± 0.15 eV, respectively, indicating type II band alignment for all three heterostructures. The significant influence of different GaN surface orientations on heterostructure performance revealed herein provides an important reference for the design and optimization of high-performance devices based on these materials in the future.