According to microwave and circuit theory, the transient response model is established after optically
controlled photoconductive semiconductor switches (PCSSs) are radiated by ultra-short light pulse. A method
for characterizing frequency spectrum characteristics of PCSSs is presented. A deep investigation of the effect
of some structural and physical parameters on the frequency characteristics of PCSSs is made. The findings
show that the carrier life and absorption coefficient of the photoconductive material for manufacturing the
switches, the width of the gap, the pulse width of the incident light, the gap capacitance, lead and parasitical
inductance have a great effect on the frequency characteristics of PCSSs. PCSSs have ability to produce THz
electromagnetic radiation and can be as Teraherz radiation source.
This research has focused on modeling of optically triggered, high gain nonlinear GaAs switches. A complete model with dynamics of deep level trap, carries, direct band-gap recombination radiation and heat involved has been constructed. The various generation and recombination mechanism have been discussed and presented. Photo-ionization, thermal emission of deep level traps, intrinsic impact ionization, standard Shockley-Read-Hall recombination, direct band-gap recombination and Auger recombination have been considered.
This research has focused on optically triggered, high gain nonlinear GaAs switches for high speed, high power microwave generation. A microstrip and a parallel-plate pusle generator have been constructed and tested. The experimental results are reported. Further studies on optically triggered, high gain, nonlinear PCSS are proposed.
An experimental and theoretical investigation of PCSS's behaviors has been performed with emphasis on 'lock-on' is intimately related to bias voltage, triggering optical energy and the concentration of deep energy level trap in PCSS's by 2D simulation with MEDICI. This effect is observed only when the three factors all satisfy corresponding threshold values that vary with operational conditions. The reason is that under such condition, the distributions of the electric field, potential, carriers and current densities in PCSS's can be notably changed, the accumulation of carriers will be formed and electric field will be gradually enhanced in some region. It ultimately reaches the critical electric field for avalanche ionization, thus avalanche multiplication of carriers occurs.
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