钝化与场板结构对AlGaN/GaN HEMT电流崩塌的影响

由于AlGaN／GaNHEMT的几何结构以及很强的极化效应，栅漏区域的电场很大，以至于电子可以从栅隧穿到AlGaN表面．隧穿的电子在表面累积，导致栅下耗尽区的电子向漏端延伸，从而引起漏极电流的下降．文中采用应力测试方法，研究了未钝化、钝化以及场板三种结构的AlGaN／GaNHEMT的电流崩塌程度．实验结果表明，钝化隔断了电子从栅隧穿到AlGaN表面的通道，场板结构能够有效降低栅边缘电场，均减少了电子从栅隧穿到表面陷阱的几率，从而使虚栅的作用减弱，有效地抑制了电流崩塌效应．

Effects of Passivation and FP Structure on Current Collapse in an AlGaN/GaN HEMT

Due to the geometry and polarization of AlGaN/GaN HEMTs, the electric field in the gate-drain region is very high, and is sufficient to produce a tunneling current from the gate metal to the surface of the AlGaN barrier layer. The electrons that tunnel to the semiconductor surface can accumulate on the surface near the gate, resulting in the extension of the depletion region and current collapse. Bias stress measurements were made to determine an AlGaN/GaN HEMT's current collapse. Surface passivation prevents the electrons from getting trapped at the surface, and a field plate suppresses the electric field at the gate edge, thereby reducing the gate leakage by a significant factor. Thus the current collapse can be effectively suppressed by surface passivation and the field-plate structure.