Investigation of Leakage Current Mechanisms in La2O3/SiO2/4H-SiC MOS Capacitors with Varied SiO2 Thickness
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- 作者：Yucheng Wang ; Renxu Jia ; Yanli Zhao ; Chengzhan Li…
- 关键词：La2O3 ; 4H ; SiC ; x ; ray photoelectron spectroscopy ; current leakage mechanism
- 刊名：Journal of Electronic Materials
- 出版年：2016
- 出版时间：November 2016
- 年：2016
- 卷：45
- 期：11
- 页码：5600-5605
- 全文大小：632 KB
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Chemistry
Optical and Electronic Materials
Characterization and Evaluation Materials
Electronics, Microelectronics and Instrumentation
Solid State Physics and Spectroscopy - 出版者：Springer Boston
- ISSN：1543-186X
- 卷排序：45
文摘
In this study, the material and electrical properties of La2O3/SiO2/4H-SiC metal–oxide–semiconductor (MOS) capacitors are systematically characterized. Thermal oxidization SiO2 with varying thickness (0 nm, 3.36 nm, 5 nm, 8 nm, and 30 nm) were coated with La2O3 using atomic layer deposition on n-type 4H-SiC. The stacking oxides were measured using atomic force microscopy, transmission electron microscopy, and x-ray photoelectron spectroscopy, and the MOS capacitors were measured by capacitance–voltage and current–voltage measurements. The results demonstrate that the main gate current leakage mechanisms are dependent on the thickness of the SiO2 oxide under the applied electric field. The primary mechanism for current leakage from the La2O3/4H-SiC MOS capacitor follows the Schottky emission mechanism due to its low conduction band offset. In contrast, the current leakage mechanism for the capacitor with a 3.36 nm SiO2 layer follows the Poole–Frenkel emission mechanism on account of its high trap charge density in the gate dielectric and at the interface. When the thickness of the SiO2 layer increases to 8 nm, lower leakage current is observed by reason of the low trap charge density and high conduction band offset when E ≤ 5 MV/cm. As the electric field strength increases to 5 MV/cm and 5.88 MV/cm (30 nm SiO2: 4.8 MV/cm), the main current leakage mechanism changes to the Fowler–Nordheim tunneling mechanism, which indicates that the La2O3/SiO2 stacking structure can improve the properties of MOS capacitors.