Review of Recent Progress on Vertical GaN-Based PN Diodes

Taofei Pu,Hsien-Chin Chiu,Hao-Chung Kuo,Ke Xu,Usman Younis,Xinke Liu

doi:10.1186/s11671-021-03554-7

Abstract

As a representative wide bandgap semiconductor material, gallium nitride (GaN) has attracted increasing attention because of its superior material properties (e.g., high electron mobility, high electron saturation velocity, and critical electric field). Vertical GaN devices have been investigated, are regarded as one of the most promising candidates for power electronics application, and are characterized by the capacity for high voltage, high current, and high breakdown voltage. Among those devices, vertical GaN-based PN junction diode (PND) has been considerably investigated and shows great performance progress on the basis of high epitaxy quality and device structure design. However, its device epitaxy quality requires further improvement. In terms of device electric performance, the electrical field crowding effect at the device edge is an urgent issue, which results in premature breakdown and limits the releasing superiorities of the GaN material, but is currently alleviated by edge termination. This review emphasizes the advances in material epitaxial growth and edge terminal techniques, followed by the exploration of the current GaN developments and potential advantages over silicon carbon (SiC) for materials and devices, the differences between GaN Schottky barrier diodes (SBDs) and PNDs as regards mechanisms and features, and the advantages of vertical devices over their lateral counterparts. Then, the review provides an outlook and reveals the design trend of vertical GaN PND utilized for a power system, including with an inchoate vertical GaN PND.

Highlights

Global energy consumption is rising much more rapidly than in the past few decades because of the rapid growth in industry and economy
This review provides an outlook and reveals the design trend of vertical gallium nitride (GaN) PN junction diode (PND) utilized for a power system, including inchoate vertical GaN PNDs
GaN Substrate of Vertical PNDs As a mainstream epitaxial process, vertical device epitaxial layers are currently mainly grown by metalorganic chemical vapor deposition (MOCVD) on conductive GaN substrates fabricated by hydride vapor phase epitaxy (HVPE)

Summary

Introduction

Global energy consumption is rising much more rapidly than in the past few decades because of the rapid growth in industry and economy. Silicon-based devices are currently the dominant type among power devices [1]. Among these power devices, the insulated gate bipolar transistor (IGBTs) structures play a significant role and display a growing trend toward the replacement of the power bipolar junction transistor (BJT) and metal oxide semiconductor field effect transistor (MOSFET) since the invention of the IGBTs. Given its outstanding properties, GaN is one of wide bandgap semiconductor materials (including SiC, GaN, Ga2O3 and diamond) capable of fabricating power devices with a low capacitance and resistance for a specified breakdown voltage with respect to the Si-based devices. GaN-based devices with low energy consumption, high power densities, and high conversion efficiency for power electronic systems are expected.

Thermal conductivity BFOM

Material Epitaxy Growth

GaN Limit