Research on the Failure Mechanism of High-Power GaAs PCSS

This paper presents an experimental study on the failure mechanism of high-power Gallium Arsenide (GaAs)-based photoconductive semiconductor switches (PCSS). Two of the typical failure scenarios of high-power GaAs PCSS are discussed: 1) a failure of a 3-mm-gap GaAs PCSS at output current of 45 A and 2) the failure of two 2-mm-gap GaAs PCSSs at output currents of 1.45 and 1.8 kA, respectively. The failure mechanisms of these two cases are analyzed and summarized as follows: The failure of high-power GaAs PCSS is mainly dominated by the development of current filaments under low output currents. A large number of energetic carriers in the bulk region of the current filament can cause the dot damage. When the dot damage is dense enough to form a continuous chain connecting the PCSS electrodes, a damage path is created and a catastrophic breakdown occurs. The thermal stress is the main cause of the failure of high-power GaAs PCSS under high current scenarios. The stress can cause local microscopic fracture on the surface of PCSS. At the time when these local microscopic fractures reach a critical level, a macroscopic fracture occurs resulting in a disintegration of the high-power PCSS.