A Breakdown Enhanced AlGaN/GaN Schottky Barrier Diode with the T-Anode Position Deep into the Bottom Buffer Layer.

Youlei Sun,Jianxiang Tang,Wenju Wang,Ying Wang,Xiaofei Kuang,Yifei Huang

doi:10.3390/mi10020091

Abstract

In this paper, an AlGaN/GaN Schottky barrier diode (SBD) with the T-anode located deep into the bottom buffer layer in combination with field plates (TAI-BBF FPs SBD) is proposed. The electrical characteristics of the proposed structure and the conventional AlGaN/GaN SBD with gated edge termination (GET SBD) were simulated and compared using a Technology Computer Aided Design (TCAD) tool. The results proved that the breakdown voltage (VBK) in the proposed structure was tremendously improved when compared to the GET SBD. This enhancement is attributed to the suppression of the anode tunneling current by the T-anode and the redistribution of the electric field in the anode–cathode region induced by the field plates (FPs). Moreover, the T-anode had a negligible effect on the two-dimensional electron gas (2DEG) in the channel layer, so there is no deterioration in the forward characteristics. After being optimized, the proposed structure exhibited a low turn-on voltage (VT) of 0.53 V and a specific on-resistance (RON,sp) of 0.32 mΩ·cm2, which was similar to the GET SBD. Meanwhile, the TAI-BBF FP SBD with an anode-cathode spacing of 5 μm achieved a VBK of 1252 V, which was enhanced almost six times compared to the GET SBD with a VBK of 213 V.

Highlights

At present, most power semiconductor devices are fabricated from Si materials, but as the process progresses, the performance of Si devices is approaching the material limit
Despite the advantage mentioned above, there are still many unsolved problems before AlGaN/GaN Schottky barrier diodes (SBD) can be used on a large scale, such as the high turn-on voltage, high anode leakage, and low breakdown voltage
Micromachines 2019, 10, 91 device had an additional T-anode with an initial length of 0.445 μm connecting the Schottky contact with the bottom buffer and two field plates located at the anode and cathode

Summary

Introduction

Most power semiconductor devices are fabricated from Si materials, but as the process progresses, the performance of Si devices is approaching the material limit. Micromachines 2019, 10, 91 device had an additional T-anode with an initial length of 0.445 μm connecting the Schottky contact with the bottom buffer and two field plates located at the anode and cathode. The effective concentration of the acceptor type traps of 2 × 1016 cm−3 [10] and 4 × 1018 cm−3 [16,17] were selected to dope into the middle and bottom buffer layers, respectively, in order to neutralize the dopants and reduce the buffer layer leakage. The middle buffer close to the channel layer could suppress the leakage current effectively, but it had an imperceptible impact on the 2DEG because of the slight p-type. The heavy p-type bottom buffer layer combining with the T-anode could play a leading role in reducing the anode leakage current.

Forwardand and ReverseCharacteristics

Electron Concentration Distribution

ThePath

Parameter

Dependence

Conclusions