2.4 kV Vertical GaN PN Diodes on Free Standing GaN Wafer Using CMOS-Compatible Contact Materials

Xinke Liu,Hsuan-Ling Kao,Cong Hu,Hou-Yu Wang,Hsiang-Chun Wang,Hsien-Chin Chiu,Feng-Tso Chien

doi:10.1109/jeds.2018.2858294

Abstract

This paper reports vertical Gallium nitride (GaN) PN diodes on free-standing GaN wafer using a complementary metal-oxide-semiconductor compatible contact materials. Static and switching current-voltage measurements have been carried out to evaluate the fabricated vertical GaN PN diodes. The vertical GaN PN diode in this paper shows turn-on voltage Von of ~3.3–3.4 V, on/off current ratio of ~2.7 $\times 10^{7}$ , and ideal factor $n$ of ~2.1. The reverse recovery time Trr is 21.2 ns and 23.2 ns, respectively, under a testing temperature of 300 K and 500 K. With an on-state resistance Ron of 3.9 m $\Omega \cdot$ cm2 and a breakdown voltage $V_{\text BR}$ of 2.4 kV, this device achieves a power device figure-of-merit $V_{\text BR}^{2}/R_{\text on}$ of $1.5\times 10^{9} \text {V}^{2} {\Omega} ^{-1} \text {cm}^{-2}$ .

Highlights

Gallium nitride (GaN)-based power rectifiers (e.g., Schottky barrier diodes, PN diodes, and PIN diodes) have been considered as the device building block used in the generation power modules (RF-DC, AC/DC etc) [1]–[5]
DEVICE STRUCTURE AND FABRICATION The epi structure used for fabricating vertical GaN PN diode in this work consists of a 30-nm p++ GaN (Mg: 2×1020 cm−3) contact layer, a 400-nm p-GaN (Mg: 1×1018 cm−3) layer, a 13-μm n− GaN drift region with a target Si doping concentration of 1.2×1016 cm−3, and a 2-μm n+ GaN buffer layer (Si: 2×1018 cm−3) on a 350-μm thick free standing 2” GaN substrate
DEVICE RESULTS AND DISCUSSION Fig. 2(a) shows the forward current IF as a function of forward voltage VF, and the turn-on voltage Von is ∼ 3.3-3.4V, which is close to the bandgap value of gallium nitride

Summary

Introduction

Gallium nitride (GaN)-based power rectifiers (e.g., Schottky barrier diodes, PN diodes, and PIN diodes) have been considered as the device building block used in the generation power modules (RF-DC, AC/DC etc) [1]–[5]. INDEX TERMS Free standing gallium nitride (GaN), power p-n diode, high breakdown voltage.

Results

Conclusion