GaN-based semiconductor devices for future power switching systems

GaN-based natural superjunction diodes and Gate Injection Transistors (GITs) with p-type gate on AlGaN/GaN hetero structure are promising power devices with lower on-state resistance and higher breakdown voltage for power switching applications. In this paper, the current status of the devices for integrated circuits and their application to power switching systems are reviewed, after explaining the basic technologies for decreasing on-resistance, increasing breakdown voltage, and suppressing current collapse. In addition, a solution to increase switching frequency of GITs for smaller system size is described. The effects of integrated circuit of DC/DC converter consisted of gate driver, high-side GIT and low-side GIT with short gate length are also examined.

I. Introduction

GaN-based materials are very promising semiconductors for power switching devices taking advantages of the superior material properties such as higher breakdown field and higher sheet carrier density of two dimensional electron gas (2DEG) at hetero interface between AlGaN/GaN. Although higher sheet carrier density of 2DEG is attractive to decrease channel resistance of GaN-based transistors, normally-off operation of the transistors is difficult. Thus much effort has been devoted to achieve GaN-based transistors with normally-off operation together with decreasing channel resistance and increasing breakdown voltage. GaN-based Gate Injection Transistor (GIT) with p-type gate on AlGaN/GaN hetero structure is a solution to overcome them.