Optimization of selective-area regrown n-GaN via MOCVD for high-frequency HEMT
Author(s): Zhang, L (Zhang, Lian); Cheng, Z (Cheng, Zhe); He, YW (He, Yawei); Xu, JX (Xu, Jianxing); Jia, LF (Jia, Lifang); Wang, XY (Wang, Xinyuan); Zhang, SY (Zhang, Shiyong); Tan, W (Tan, Wei); Zhang, Y (Zhang, Yun)
Source: APPLIED PHYSICS LETTERS Volume: 119 Issue: 26 Article Number: 262104 DOI: 10.1063/5.0077937 Published: DEC 27 2021
Abstract: The selective-area regrowth (SAG) n-type GaN source/drain electrode has been widely used in high electron mobility transistors (HEMTs) for high-frequency applications. Previous studies focused only on device performances, but not on SAG n(+)-GaN in devices. This paper studies electron concentration and mobility of SAG n(+)-GaN on InAlN/GaN HEMTs via metal-organic chemical vapor deposition (MOCVD). It is revealed that electron mobility of SAG GaN is significantly affected by thickness. The decrease in mobility in a thin GaN may be attributed to regrowth interface defects. A gas flow model on the regrowth region is proposed to guide the regrowth of SAG GaN for improving the electron mobility. A high electron mobility of 138cm(2)/Vs with an electron concentration of 5.2x10(19)/cm(3) is obtained from an 80-nm n(+)-GaN with the regrowth width of 10 mu m. Due to the high doping level, the nonalloy metal-semiconductor contact resistance (Rm-GaN) is as low as 0.041 Omega mm. The interface resistance (R-int) between GaN and 2DEG is extracted using transfer length measurement (TLM) models and found to be 0.106 Omega mm. The on-resistance (R-on) is 0.753 Omega mm for InAlN/GaN HEMT with a source-drain metal spacing (L-sd metal) of 2 mu m. Published under an exclusive license by AIP Publishing.
Accession Number: WOS:000755254700021
ISSN: 0003-6951
eISSN: 1077-3118
