Energy-band alignment of atomic layer deposited (HfO2)x(Al2O3)1-x gate dielectrics on 4H-SiC
Jia Ren-Xu (贾仁需)a, Dong Lin-Peng (董林鹏)a, Niu Ying-Xi (钮应喜)b, Li Cheng-Zhan (李诚瞻)c, Song Qing-Wen (宋庆文)a, Tang Xiao-Yan (汤晓燕)a, Yang Fei (杨霏)b, Zhang Yu-Ming (张玉明)a
a School of Microelectronics, Xidian University, Xi'an 710071, China;
b State Grid Smart Grid Research Institute, Beijing 100192, China;
c Zhuzhou CSR Times Electric Co., Ltd., Zhuzhou 412001, China
We study a series of (HfO2)x(Al2O3)1-x/4H-SiC MOS capacitors. It is shown that the conduction band offset of HfO2 is 0.5 eV and the conduction band offset of HfAlO is 1.11-1.72 eV. The conduction band offsets of (HfO2)x(Al2O3)1-x are increased with the increase of the Al composition, and the (HfO2)x(Al2O3)1-x offer acceptable barrier heights (> 1 eV) for both electrons and holes. With a higher conduction band offset, (HfO2)x(Al2O3)1-x/4H-SiC MOS capacitors result in a ~ 3 orders of magnitude lower gate leakage current at an effective electric field of 15 MV/cm and roughly the same effective breakdown field of ~ 25 MV/cm compared to HfO2. Considering the tradeoff among the band gap, the band offset, and the dielectric constant, we conclude that the optimum Al2O3 concentration is about 30% for an alternative gate dielectric in 4H-SiC power MOS-based transistors.
Project supported by the National Natural Science Foundation of China (Grant Nos. 51272202 and 61234006) and the Science Project of State Grid, China (Grant No. SGRI-WD-71-14-004).
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