New findings of pulsed surface breakdown along silicon in vacuum

Leakage and partial-breakdown characteristics of high-purity (ρ>30 kΩ-cm) bulk silicon in vacuum (~10^-6 torr) under impulse voltage stress (0.39/10 μs) are discussed. The discussion is focused on the mechanism associated with the partial-breakdown phase. The mechanism is believed to be due mainly to injection followed by avalanche breakdown, from many local spots at the cathode contact. Thermal and field emission processes are also proposed, along with the avalanche process, to describe the partial breakdown phase of silicon. These experimental findings clearly show that the injection process is a process through the bulk rather than along the surface of a specimen. More importantly, the final surface flashover is believed to be initiated by the bulk injection mechanism