Investigation on Dynamic Characteristics of AlGaN/GaN Lateral Schottky Barrier Diode.

Haitao Zhang,Hao Wu,Tianchun Ye,Xinyu Liu,Xuanwu Kang,Ke Wei,Yingkui Zheng,Zhi Jin

doi:10.3390/mi12111296

Abstract

This work investigates the transient characteristics of an AlGaN/GaN lateral Schottky barrier diode (SBD) and its recovery process with a dedicated dynamic measurement system. Both static and dynamic characteristics were measured, analyzed with the consideration of acceptor/donor traps in the C-doped buffer and GaN channel, and verified by Silvaco TCAD (technology computer aided design) simulations. The energy band, electric field, and electron concentration were monitored in the transient simulation to study the origin of the current collapse in the SBD. Using the verified model, the impact of carbon doping concentration in the buffer and the thickness of the unintentionally doped (UID) GaN channel in the transient behavior was estimated. Several observations were revealed. Firstly, the traps in the GaN channel and buffer layer have a significant impact on the current collapse of the device. A severe deterioration of current collapse can be observed in the SBDs with increasing density of acceptor-like traps. Secondly, the current collapse increases with the thinner UID GaN channel layer. This well-performed simulation model shows promise to be utilized for the dynamic performance optimization of GaN lateral devices.

Highlights

A GaN-based Schottky barrier diode (SBD) is a promising device for next-generation electrical power systems, attributed to its superior material properties, such as high mobility, high electric breakdown strength, and high electron saturation velocity
The process flow of the GaN SBD is compatible with GaN high electron mobility transistor (HEMT) and metal-insulator-semiconductor HEMT (MIS-HEMT), promising for its integration in the smart GaN platform
We mainly focus on physics-based simulation of the thin-barrier AlGaN/GaN SBD

Summary

Introduction

A GaN-based Schottky barrier diode (SBD) is a promising device for next-generation electrical power systems, attributed to its superior material properties, such as high mobility, high electric breakdown strength, and high electron saturation velocity. A recess-free AlGaN/GaN heterojunction Schottky diode structure with a thin barrier was proposed, with a two dimensional electron gas (2DEG) being effectively preserved by silicon nitride (SiNx ) passivation grown by low pressure chemical vapor deposition (LPCVD) [12,13]. The substrate is set as a float in the simulation process so as to study the influence of the electrical stress caused by the horizontal potential difference on the device. STS8200 tester has been modified to work bidirectionally, including a conventional static test on GaN SBD and current collapse, as well as achieving a voltage switch in a very short period of time. SBDs with different anode and cathode spacing were fabricated for static and dynamic electrical measurement and simulation. The energy band, electric field, and electron concentration were monitored in the transient simulation to study the origin of the current collapse in the SBD. A more severe current collapse is observed with a decrease in the thickness of the UID GaN channel layer

Device Characterization and Simulation

Results and Discussion

Conclusions