title: GaN as an interfacial passivation layer: tuning band offset and removing fermi level pinning for III-V MOS devices.
abstract: The use of an interfacial passivation layer is one important strategy for achieving a high quality interface between high-k and III-V materials integrated into high-mobility metal-oxide-semiconductor field-effect transistor (MOSFET) devices. Here, we propose gallium nitride (GaN) as the interfacial layer between III-V materials and hafnium oxide (HfO2). Utilizing first-principles calculations, we explore the structural and electronic properties of the GaN/HfO2 interface with respect to the interfacial oxygen contents. In the O-rich condition, an O8 interface (eight oxygen atoms at the interface, corresponding to 100% oxygen concentration) displays the most stability. By reducing the interfacial O concentration from 100 to 25%, we find that the interface formation energy increases; when sublayer oxygen vacancies exist, the interface becomes even less stable compared with O8. The band offset is also observed to be highly dependent on the interfacial oxygen concentration. Further analysis of the electronic structure shows that no interface states are present at the O8 interface. These findings indicate that the O8 interface serves as a promising candidate for high quality III-V MOS devices. Moreover, interfacial states are present when such interfacial oxygen is partially removed. The interface states, leading to Fermi level pinning, originate from unsaturated interfacial Ga atoms.
authors: College of Electronic Information and Optical Engineering, Nankai University , 300071 Tianjin, P. R. China.
authors: Zhaofu
authors: Z
authors: Zhang
authors: Ruyue
authors: R
authors: Cao
authors: Changhong
authors: C
authors: Wang
authors: Hao-Bo
authors: HB
authors: Li
authors: Hong
authors: H
authors: Dong
authors: Wei-Hua
authors: WH
authors: Wang
authors: Feng
authors: F
authors: Lu
authors: Yahui
authors: Y
authors: Cheng
authors: Xinjian
authors: X
authors: Xie
authors: Hui
authors: H
authors: Liu
authors: Kyeongjae
authors: K
authors: Cho
authors: Robert
authors: R
authors: Wallace
authors: Weichao
authors: W
authors: Wang
keywords: Fermi level pinning; GaN/HfO2 interface; band offsets; first-principles study; interfacial formation energy