5 eV), and large conduction band offset (approximately 1.97 eV) [25, 29–31]. Despite that, the presence of oxygen-related defects, changes in compositional homogeneity of Y2O3, and formation of interfacial layer (IL) are of particular concern as either of these Salubrinal cell line factors

might alter the bandgap of Y2O3 and band alignment of Y2O3 with respect to the GaN, which would influence the J-E characteristic of the MOS structure. Li et al. has reported previously that J-E characteristic of the MOS structure is dependent on the thickness of IL, wherein interface quality of the atomic layer deposited HfO2 on Si can be altered via the IL thickness [32]. In Veliparib order to reduce oxygen-related defects and restore compositional homogeneity of Y2O3, it is essential to perform post-deposition annealing on the oxide [33]. Besides, the oxygen content near the Y2O3/GaN interface can be regulated by varying the post-deposition annealing ambient and eventually controlling the formation of IL. Therefore, engineering of the bandgap of Y2O3 gate and band alignment of Y2O3 with GaN through different PDA ambients is of technological importance. In this work, effects of different PDA ambients (oxygen (O2), argon (Ar) [25], nitrogen (N2), and forming gas (FG; 95% N2 + 5% H2)) at 400°C for 30 min on the Y2O3/GaN structure in modifying the bandgap of Y2O3 gate and band alignment

of Y2O3/GaN are presented. A correlation on the bandgap of Y2O3 gate and band alignment of Y2O3/GaN Ro 61-8048 with regard to the J-E characteristics is also discussed in this paper. Methods Prior to the deposition of 60-nm thick Y2O3 films on the commercially purchased Si-doped (n-type) GaN epitaxial layers with thickness of 7 μm and doping concentration of 1 to 9 × 1018 cm−3 grown on sapphire substrates, the wafer, which was diced into smaller pieces, were subjected

to RCA cleaning. Subsequently, these samples were loaded into a vacuum chamber of RF magnetron Bay 11-7085 sputtering system (Edwards A500, Edwards, Sanborn, NY, USA). A comprehensive description on the deposition process of Y2O3 films has been reported elsewhere [29, 30]. Then, PDA was performed in a horizontal tube furnace at 400°C in different ambients (O2, Ar, N2, and FG (95%N2 + 5% H2)) for 30 min. The heating and cooling rate of approximately 10°C/min was used for the PDA process. After the PDA process, X-ray photoelectron spectroscopy (XPS) measurements were conducted on the samples at the Research Center for Surface and Materials Science, Auckland University, New Zealand, using Kratos Axis Ultra DLD (Shimadzu, Kyoto, Japan) equipped with a monochromatic Al-Kα X-ray source (hv = 1486.69 eV). The spectra of the survey scan were obtained at a low pass energy of 160 eV with an energy resolution of 0.1 eV, and the photoelectron take-off angle was fixed at 0° with respect to the surface normal.