Enhanced gate stack stability in GaN transistors with gate dielectric of bilayer SiNx by low pressure chemical vapor deposition

• Published in: Applied physics letters 2018-12, Vol.113 (23)
• Main Authors: Huang, Tongde, Jiang, Huaxing, Bergsten, Johan, Lau, Kei May, Rorsman, Niklas
• Format: Article
• Language: English
• Subjects: Aluminum gallium nitrides; Applied physics; Bilayers; Chemical vapor deposition; Current leakage; Dielectrics; Electrical resistivity; Electron mobility; Gallium nitrides; Gates; High electron mobility transistors; Interlayers; Leakage current; Low pressure; MIS (semiconductors); Organic chemistry; Semiconductor devices; Silicon; Stability; Threshold voltage; Transistors
• ISSN: 0003-6951; 1077-3118; 1077-3118
• DOI: 10.1063/1.5042809

We report enhanced gate stack stability in GaN metal insulator semiconductor high electron mobility transistors (MISHEMTs) by using a bilayer SiNx as the gate dielectric. To obtain the bilayer gate dielectric scheme, a thin Si-rich SiNx interlayer was deposited before a high-resistivity SiNx layer by low pressure chemical vapor deposition. The Si-rich SiNx can effectively suppress the trapping phenomenon at the interface of the dielectric/AlGaN barrier. The upper high-resistivity SiNx layer can greatly block the gate leakage current to enable a large gate swing. Compared with the MISHEMTs using a single Si-rich or high-resistivity SiNx layer, the MISHEMTs with a bilayer gate dielectric take the advantages of both, realizing a gate stack with a stable threshold voltage and low leakage current. These results thus present great potential for developing high-performance GaN MISHEMTs using the bilayer SiNx gate dielectric scheme for highly efficient power applications.