选择区域外延槽栅结构GaN常关型MOSFET的研究

高性能GaN常关型功率开关器件的实现是目前研究的热点。槽栅结构GaN常关型MOSFET以其栅压摆幅冗余度大、栅极漏电流小等优势受到广泛关注。制备槽栅结构GaN常关型MOSFET需要的刻蚀方法会在栅极沟道引入缺陷,影响器件的稳定性。首先,提出选择区域外延方法制备槽栅结构GaN常关型MOSFET,期望避免刻蚀对栅极沟道的损伤;再通过改进选择区域外延工艺(包括二次生长界面和异质结构界面的分离及抑制背景施主杂质),使得二次生长的异质结构质量达到标准异质结构水平。研究结果表明,选择区域外延方法能够有效保护栅极导通界面,使器件具备优越的阈值电压稳定性;同时也证明了选择区域外延方法制备槽栅结构GaN常关型MOSFET的可行性与优越性。

Research on GaN Based Trench Gate Normally-off MOSFET Using Selective Area Growth Technique

The realization of high performance GaN normally-off power switching device is a hotspot in present study. Trench gate MOSFET is attractive for its large gate voltage swing and low gate leakage current. The trench gate structure is commonly formed by etch method which will introduce defect at metal-oxide-semiconductor(MOS)channel. First, the selective area growth(SAG)technique is proposed to realize trench gate normally-off MOSFET for the purpose of avoiding defect at gate channel in this paper. Then through the improvement of SAG technique including separating the SAG interface and hetero-interface and suppressing the background doping, high quality AlGaN/GaN heterostructure is regrown. The research result shows that SAG technique can retain the smooth surface in gate channel leading to superior threshold voltage stability which demonstrates SAG technique as the promising way for fabricating high performance trench gate normally-off MOSFET.