Theory Study Of Luminous Charge Domain In Semi-Insulated GaAs Photoconductive Semiconductor Switch

Due to the excellent characteristics, Semi-insulated GaAs Photoconductive semiconductor Switches (PCSS's) can be widely used in many fields such as ultrahigh speed electronics, high power pulse, ultra-wideband radar, technology of pulse power and Terahertz (THz). Many attentions have been paid in the domain of Semiconductor and optics on PCSS's. After the theory and application of linear mode have been used in practice, the theory and application of nonlinear mode also have been basically accomplished. Based on the equations of photoconductive switch device and the transfer electron effect of GaAs multi-valley structure, a better model of luminous charge domain can be built to explain the linear and nonlinear phenomenon in PCSS's.First, from the multi-valley structure of GaAs semiconductor, the transfer electron effect was introduced. The reasons of the difference between dipole domain and luminous charge domain were analyzed by discussing the establishment and transport process of dipole domain in n-GaAs and luminous charge domain in SI-GaAs. Second, based on the basically equations of drift-diffusion, the device equations of PCSS's were built. Considering the theory of collision ionization, stream and filar current, many kinds of nonlinear phenomenon were explained further. And the long delay time in nonlinear phenomenon was explained by using the trap effect of EL2 deep level. At last, the reason of lower signal to noise ratio (SNR) in THz radiation from GaAs photoconduction antenna was analyzed. Then based on the analysis, the way which can improve the power of THz radiation and SNR was found. The periodical changed bias was added by controlling of external circuit, and the luminous charge domain (or the electron accumulation horizon in which the domain were not formed) was quenched. Carriers which were existed in devices were accelerated time after time and were put into transfer electron effect by the characteristic of long lifetime of carriers. This way can be used to improve the power and SNR of THz radiation. The result was proved by Monte Carlo simulation.