GaN基HEMT失效热点行为研究

Study on the Failure Hot Spots Behavior in GaN-Based HEMT

研究了GaN基HEMT器件的失效热点行为。当V_(GS)>V_(th)时,漏极电流I_(D)主要为漏-源导通电流I_(DS),输运机制为漂移;当V_(GS)<V_(th)时,I_(D)主要为反向栅-漏电流I_(GD),输运机制为与可导位错有关的Fowler-Nordheim隧穿。通过分析V_(GS)和I_(DS)变化对热点分布的影响,表明栅极边界耗尽沟道内形成的强横向电场与势垒层内的强垂直电场分别是I_(DS)和I_(GD)电流形成热点的主要原因;同时,还测量了热点的微光光谱,并根据临界电场与最大光子能量得到了电子的平均自由程,约为60 nm。

The behavior of the failure hot spots in GaN based HEMT devices was studied.When V_(GS)>V_(th),the drain current I_(D)was mainly the drain-source conduction current I_(DS),and the transport mechanism was drift.When V_(GS)<V_(th),I_(D)was mainly the reverse gate leakage current I_(GD),and the transport mechanism was Fowler Nordheim tunneling related to conductive dislocations.By analyzing the effects of different V_(GS)and I_(DS)on the hot spot distribution,it was shown that the transverse electric field formed by the depletion channel near the drain side of the gate boundary and the vertical electric field in the barrier layer were the main reasons for the hot spots of I_(DS)and I_(GD)current,respectively.The low-light spectrum of hot spots was measured.According to the critical electric field and the maximum photon energy,the average free path of the electron was about 60nm.