Duan Tian Li, Pan Ji Sheng, Wang Ning, Cheng Kai, Yu Hong Yu
Southern University of Science and Technology, Shenzhen, 518055, People's Republic of China.
Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, #08-03, Singapore, 138634, Singapore.
Nanoscale Res Lett. 2017 Aug 17;12(1):499. doi: 10.1186/s11671-017-2271-x.
The surface polarization of Ga-face gallium nitride (GaN) (2 nm)/AlGaN (22 nm)/GaN channel (150 nm)/buffer/Si with AlO capping layer is investigated by angle-resolved X-ray photoelectron spectroscopy (ARXPS). It is found that the energy band varies from upward bending to downward bending in the interface region, which is believed to be corresponding to the polarization variation. An interfacial layer is formed between top GaN and AlO due to the occurrence of Ga-N bond break and Ga-O bond forming during AlO deposition via the atomic layer deposition (ALD). This interfacial layer is believed to eliminate the GaN polarization, thus reducing the polarization-induced negative charges. Furthermore, this interfacial layer plays a key role for the introduction of the positive charges which lead the energy band downward. Finally, a N annealing at 400 °C is observed to enhance the interfacial layer growth thus increasing the density of positive charges.
通过角分辨X射线光电子能谱（ARXPS）研究了具有AlO覆盖层的Ga面氮化镓（GaN）（2纳米）/AlGaN（22纳米）/GaN沟道（150纳米）/缓冲层/Si的表面极化。研究发现，在界面区域能带从向上弯曲变为向下弯曲，这被认为与极化变化相对应。在通过原子层沉积（ALD）沉积AlO期间，由于Ga-N键断裂和Ga-O键形成，在顶部GaN和AlO之间形成了一个界面层。据信该界面层消除了GaN极化，从而减少了极化诱导的负电荷。此外，该界面层对于引入导致能带向下的正电荷起着关键作用。最后，观察到在400°C下进行N退火可促进界面层生长，从而增加正电荷密度。
