Investigation of Multi-Mesa-Channel-Structured AlGaN/GaN MOSHEMTs with SiO2 Gate Oxide Layer

Jhang-Jie Jian,Hsin-Ying Lee,Edward-Yi Chang,Ching-Ting Lee

doi:10.3390/coatings11121494

Abstract

In this study, an electron-beam lithography system was employed to pattern 80-nm-wide and 980-nm-spaced multi-mesa-channel for fabricating AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs). Since the structure of multi-mesa-channel could enhance gate control capabilities and reduce the self-heating effect in the channel, the performance of the MOSHEMTs could be obviously improved. The direct current performance metrics of the multi-mesa-channel-structured MOSHEMTs, such as a saturation drain-source current of 929 mA/mm, maximum extrinsic transconductance of 223 mS/mm, and on-resistance of 2.1 Ω-mm, were much better than those of the planar-structured MOSHEMTs. Moreover, the threshold voltage of the multi-mesa-channel-structured MOSHEMTs shifted toward positive voltage from −2.6 to −0.6 V, which was attributed to the better gate control capability. Moreover, the multi-mesa-channel-structured MOSHEMTs also had superior high-frequency and low-frequency noise performance. A low Hooge’s coefficient of 1.17 × 10−6 was obtained.

Highlights

Due to the rapid requirement of emerging applications such as electric vehicles, fifth generation (5G) wireless systems, and renewable energy systems, high-power and high-frequency devices have attracted significant attention. Both gallium nitride (GaN)-based and silicon carbide (SiC)-based materials are used in high-power and high-frequency amplifiers [1,2,3,4], SiC is much more expensive than GaN [5]
To improve the power-handling capabilities and enhance operation voltage by reducing gate leakage current, AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) have been used to replace metal-semiconductor HEMTs and have become mainstream high-frequency devices and high-power devices used in various systems [6]
Despite the success of planar-structured devices, several studies have reported that gate control capability and self-heating dissipation could be improved by employing a multi-mesa-channel (MMC) structure in AlGaN/GaN MOSHEMTs [18,19,20,21,22,23]

Summary

Introduction

Due to the rapid requirement of emerging applications such as electric vehicles, fifth generation (5G) wireless systems, and renewable energy systems, high-power and high-frequency devices have attracted significant attention. To improve the power-handling capabilities and enhance operation voltage by reducing gate leakage current, AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) have been used to replace metal-semiconductor HEMTs and have become mainstream high-frequency devices and high-power devices used in various systems [6].

Results

Conclusion