Analysis of Oxidized p-GaN Films Directly Grown Using Bias-Assisted Photoelectrochemical Method

Retardation Mechanism of Ultrathin Al2O3 Interlayer on Y2O3 Passivated Gallium Nitride Surface

“…With this, IL consisting of Al–Ga–O–N is formed, as observed in region 4 in XPS depth profiling (Figure ) and EELS line scan (Figure ) for all of the investigated samples. In order to determine the compound present in the region of the IL for all of the investigated samples, XPS core level spectra of Al 2p, Ga 2p, O 1s, and N 1s have been carried out and Al–O, Al–N, Ga–O, and Ga–O–N compounds − have been detected in this region (Figure ).…”

“…The diffusion of Ga 3+ and Y 3+ to α-Al 2 O 3 interlayer (region 3) can be testified on the basis of the detection of Ga profile in region 3 through EELS line scan (Figure ) and XPS depth profiling analysis (Figure ) as well as Y profile from XPS depth profiling analysis (Figure ). It was resolved from XPS core level spectra of Y 3d, Al 2p, O 1s, Ga 2p, and N 1s that Y–O, Y–N, Al–O, Al–N, Ga–O, and Ga–O–N compounds − are formed in region 3 (Figure ). Since region 3 has attained charge neutrality through the diffusion of Ga 3+ , Y 3+ , N 3– , and oxygen species to the α-Al 2 O 3 interlayer, the excess of either ions in region 3 will diffuse outward to region 2 and/or inward to region 4.…”

GaN-based p-type metal-oxide–semiconductor devices with a gate oxide layer grown by a bias-assisted photoelectrochemical oxidation method

“…Therefore, the asgrown oxide layers were not suitably used in the following device fabrication processes. To overcome this problem, the as-grown oxide layers were annealed in a furnace at 700 • C in an O 2 ambient for 2 h. The measured XRD patterns indicated that the annealed oxide films exhibited a β-Ga 2 O 3 crystalline phase [24], which showed good chemical stability and was suitable for use in the following device fabrication process. In addition, the surface of the annealed oxide films looked smooth and no cracks on them.…”

GaN-based Metal-Oxide-Semiconductor Devices

“…The holes and electrons ionized in the space-charge layer can move toward the p-GaN layer and H 3 PO 4 /p-GaN interface, respectively, due to the built-in electric field. These induced holes would move into the bulk layer under the influence of the built-in electrical field if p-GaN is made contact with electrolytic solution (Huang et al, 2009). This may explain why oxidizing p-GaN using traditional PEC oxidation is considered difficult.…”