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

• Published in: ACS applied materials & interfaces 2017-05, Vol.9 (20), p.17576-17585
• Main Authors: Kim, Kwangeun, Ryu, Jae Ha, Kim, Jisoo, Cho, Sang June, Liu, Dong, Park, Jeongpil, Lee, In-Kyu, Moody, Baxter, Zhou, Weidong, Albrecht, John, Ma, Zhenqiang
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.7b01549

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/O3) treatment of the GaN surface on the energy band bending of atomic-layer-deposition (ALD) Al2O3 coated Ga-polar GaN were studied. The UV/O3 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 Al2O3/GaN interfaces. The UV/O3 treatment increases the surface energy of the Ga-polar GaN, improves the uniformity of Al2O3 deposition, and changes the amount of trapped charges in the ALD layer. The positively charged surface states formed by the UV/O3 treatment-induced surface factors externally screen the effect of polarization charges in the GaN, in effect, determining the eventual energy band bending at the Al2O3/GaN interfaces. An optimal UV/O3 treatment condition also exists for realizing the “best” interface conditions. The study of UV/O3 treatment effect on the band alignments at the dielectric/III-nitride interfaces will be valuable for applications of transistors, light-emitting diodes, and photovoltaics.