Normally-Off p-GaN Gated AlGaN/GaN MIS-HEMTs with ALD-Grown Al2O3/AlN Composite Gate Insulator.

Hsien-Chin Chiu,Shinn-Yn Lin,Feng-Tso Chien,Hsuan-Ling Kao,Chi-Chuan Chiu,Chia-Hao Liu,Chong-Rong Huang,Hsiang-Chun Wang

doi:10.3390/membranes11100727

Hsien-Chin Chiu, Shinn-Yn Lin + Show 6 more

Open Access

https://doi.org/10.3390/membranes11100727

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Abstract

A metal–insulator–semiconductor p-type GaN gate high-electron-mobility transistor (MIS-HEMT) with an Al2O3/AlN gate insulator layer deposited through atomic layer deposition was investigated. A favorable interface was observed between the selected insulator, atomic layer deposition–grown AlN, and GaN. A conventional p-type enhancement-mode GaN device without an Al2O3/AlN layer, known as a Schottky gate (SG) p-GaN HEMT, was also fabricated for comparison. Because of the presence of the Al2O3/AlN layer, the gate leakage and threshold voltage of the MIS-HEMT improved more than those of the SG-HEMT did. Additionally, a high turn-on voltage was obtained. The MIS-HEMT was shown to be reliable with a long lifetime. Hence, growing a high-quality Al2O3/AlN layer in an HEMT can help realize a high-performance enhancement-mode transistor with high stability, a large gate swing region, and high reliability.

Highlights

High-electron-mobility transistors (HEMTs) are crucial for high-frequency and highpower applications because of their outstanding thermal properties, high breakdown fields, and high mobility levels
A positive threshold voltage can be obtained in HEMTs with p-type GaN layers, without affecting channel mobility; strategies involving the use of a p-type GaN layer are widely considered as the most effective among the strategies mentioned above
The turn-on voltage was higher than 20 V, with a threshold voltage of 3 V and a high saturation drain current of approximately 363

Summary

Introduction

High-electron-mobility transistors (HEMTs) are crucial for high-frequency and highpower applications because of their outstanding thermal properties, high breakdown fields, and high mobility levels. For fail-safe reasons, the power integrated circuits usually require high-performance normally-off devices [1] Several strategies, such as the use of fluorine ion treatment [2], gate recess [3], and a p-type GaN cap layer [4,5], have been employed in normally-off HEMT devices. To control the etching depth, an AlN etch stop layer [6] is inserted between the p-GaN and barrier layers. Ing depth, an AlN etch stop layer [6] is inserted between the p-GaN and barrier layers This helps achieve highly selective etching to obtain superior etching uniformity, lower sgealteectlievaekaegtceh, ianngdtloowobetradinynsaumpeicrioonr -ertecshisitnagncuen. Inettchhiisnsgtuadnyd, itnocmreiansiemtihzee gthaetedsewfeicntgs rthegaitomn,awy eardiseepaofstietredp-AGla2ON3 eatncdhinAglNanldayinercsre[a1s1e] tohne tghaetesuswrfiancge roefgtihoen,dweveidceepthosriotuedghAal2tOom aicnldayAelrNdleapyoesrsit[io11n](oAnLtDhe); stuherfsaecelaoyfetrhseadlseoviicmepthrorovuedghthaetodmeivcilcaeypererdfeoprmosaitnicoen, (iAncLrDea);sethdestheelatyuerrns-oalnsoviomltpagroev, erdetdhuecdedevtihcee gpaetrefolermakaangceec, uinrcrreenats, eadndthiencturerans-eodntvhoeltdaegvei,creesdtuabceilditythaetghaigtehleteamkapgeeractuurrreesn. t, and increased the device stability at high temperatures

Device Structure

Conclusions