半导体闪络引起的材料表面破坏现象研究

长期以来，沿半导体表面的闪络现象使得很多高功率半导体器件只能工作在相对较低的电场下，限制了它们的发展，而目前对半导体闪络的物理机理尚不明确.开展了冲击高压下Si及GaAs半导体的表面闪络实验，通过红外摄影观察到闪络过程中半导体表面存在的细丝状电流通道，且发现电极中央区域会出现明显红外辐射集中点.在闪络后的材料表面可以观察到细丝状破坏现象，其中在破坏后的n100型Si材料表面的细丝通道周围发现了凹坑形结构，凹坑中心存在圆锥状突起.结合电极边缘细丝状的破坏现象，讨论了电极边缘的热注入和内部多数载流子的弛豫特性 关键词： 半导体 表面闪络 细丝电流 表面破坏

Investigation on surface damage phenomena induced by flashover across semiconductor

The flashover across semiconducting materials disables many high power semiconductor devices from their further application under high electric field. Up to now, the physical mechanism of the flashover was still not understood clearly. Surface flashover experiments of silicon and gallium arsenide were performed under pulsed high voltage. The filament current channels on their surface were observed in the infrared photographs, and the infrared radiation bright spot was found in the central region between the electrodes. On the surface of different samples undergone flashover events for several times, the filament damage phenomena were observed, and for the n100 silicon sample, some circular pits were found around the filament channel, with a conical jut in the center of each pit. According to the damage phenomena at the edge of electrodes, the thermal injection and relaxation characteristics of majority carriers were discussed. An injection model induced by minority carriers was proposed, which emphasizes the surface field enhancement by non-equilibrium carrier channel, which possibly leads to the ionization of the ambient gas above the filament channel. The model was consistent with the observed experimental results.