Band-Bending of Ga-Polar GaN Interfaced with Al₂O₃ through Ultraviolet/Ozone Treatment

Abstract

Understanding the band bending at the interface of GaN/dielectric under different surface treatment conditions is critically important for device design, device performance, and device reliability. The effects of ultraviolet/ozone (UV/O) treatment of the GaN surface on the energy band bending of atomic-layer-deposition (ALD) AlO coated Ga-polar GaN were studied. The UV/O treatment and post-ALD anneal can be used to effectively vary the band bending, the valence band offset, conduction band offset, and the interface dipole at the AlO/GaN interfaces. The UV/O treatment increases the surface energy of the Ga-polar GaN, improves the uniformity of AlO deposition, and changes the amount of trapped charges in the ALD layer. The positively charged surface states formed by the UV/O treatment-induced surface factors externally screen the effect of polarization charges in the GaN, in effect, determining the eventual energy band bending at the AlO/GaN interfaces. An optimal UV/O treatment condition also exists for realizing the "best" interface conditions. The study of UV/O treatment effect on the band alignments at the dielectric/III-nitride interfaces will be valuable for applications of transistors, light-emitting diodes, and photovoltaics.

Study of an Al2O3/GaN Interface for Normally Off MOS-Channel High-Electron-Mobility Transistors Using XPS Characterization: The Impact of Wet Surface Treatment on Threshold Voltage VTH

“…As reported in the literature, the modification of binding energy as measured by XPS can be explained by the presence of charges or dipoles, which shift the energy levels. 18,26 Spectral shifts on Figure 5b,c underline band-bending variations at an Al 2 O 3 /GaN interface when the sample is etched or cleaned with HF. Extracted peak positions are summarized in Figure 5d.…”

“…Therefore, this effect is probably related to GaN band-bending changes due to varying charge densities at the Al 2 O 3 /GaN interface. As reported in the literature, the modification of binding energy as measured by XPS can be explained by the presence of charges or dipoles, which shift the energy levels. , …”

Lattice Structure and Bandgap Control of 2D GaN Grown on Graphene/Si Heterostructures

“…Moreover, Figure e reveals the peak of Ga 3d core level spectrum. The peaks observed at 23.3 and 19.2 eV are related to O 2s and GaN bonds, respectively. The remaining of Ga 2p 3/2 and 3d core level spectra after graphene removal reveals the excellent stability of 2D GaN.…”

Shear-Induced Changes of Electronic Properties in Gallium Nitride

“…Besides vacancy defects, an oxygen impurity incorporating with a defect site at the surface can be another possible source that gives rise to the surface band bending. 64,65 As reported elsewhere, mechanochemical methods have been extensively used to generate surface defects in semiconductor materials to enhance photocatalytic efficiency. [3][4][5][6]20,21 It has been proven that by incorporating surface defects into the material these defects can introduce midgap states and provide adsorption sites in these materials, which led to much higher photocatalytic efficiency.…”