A photoconductive semiconductor switch vertically embedded with MISFETs for high-power high-repetition-rate application

The stagnate on the photoconductive semiconductor switch (PCSS) technology and the development potential are analyzed in the paper. It is pointed out that, if the high-gain mode of a GaAs PCSS can be rapidly quenched to exit the current lock-on state or if the dark leakage current of a GaN or SiC PCSS can be effectively suppressed, the PCSS will be capable to withstand a dc voltage of more than 150 kV and simultaneously to support a switching frequency of 1 MHz. Therefore, a novel PCSS structure, named insulated-gate photoconductive semiconductor switch (IGPCSS) [1], is presented to solve the lock-on and the leakage current problems mentioned above. The IGPCSS fabrication processes are growing three epitaxial layers on a traditional PCSS substrate and then embedding with an array of U-shape n-channel MISFET cells. The MISFET cells in the IGPCSS can not only share the bias dc voltage to dramatically decrease the leakage current and transfer itself voltage to the photoconductive area to yield higher photoelectric conversion efficiency. Next, some important design principles of IGPCSS are proposed and a GaAs IGPCSS is simulated. The simulation results show that the quenched high-gain operation mode of PCSS substrate can be realized through controlling the gate voltage of IGPCSS to lever the internal voltage distribution.