化学计量学
化学气相沉积
异质结
材料科学
金属有机气相外延
钝化
分析化学(期刊)
光电子学
纳米技术
化学
物理化学
图层(电子)
有机化学
外延
作者
Liyang Zhu,Qi Zhou,Kuangli Chen,Wei Gao,Yong Cai,Kai Cheng,Zhaoji Li,Chao Zhang
标识
DOI:10.1109/ted.2022.3188609
摘要
In this work, the impact of low-pressure chemical vapor deposition (LPCVD)-Si x N y stoichiometry on 2-D electron gas (2-DEG) transport characteristics of the AlGaN (3.9 nm)/GaN heterostructure and the underlying mechanism of increased 2-DEG density are studied, which reveals a new perspective of improving AlGaN/GaN performance by dielectric engineering. Among the AlGaN/GaN passivated by the LPCVD-Si x N y with tailored stoichiometry, the 2-DEG density and mobility in the Si-rich sample were significantly improved by 25% and 16.3% compared with the N-rich sample, respectively. Accordingly, 30% reduction in sheet resistance of AlGaN/GaN heterostructure is obtained. The potentially strained-induced enhancement of piezoelectric polarization and corresponding 2-DEG variation by the Si x N y passivation layer was excluded by the negligible change in Raman spectra among the different samples. Alternatively, the X-ray photoelectron spectroscopy (XPS) showed that the varied stoichiometry of the Si x N y enables a discernible modulation effect of heterostructure energy-band. The reduced surface potential in the sample passivated by Si-rich Si x N y attributes to the pronounced Ga dangling bonds (DBs) at the LPCVD-Si x N y /AlGaN interfaces, which provides the near-conduction band (NCB) states and leads to enhanced 2-DEG accumulation.
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