Gain GaAs Photoconductive Semiconductor Switches Research Articles

Carrier Injection in High Gain GaAs Photoconductive Semiconductor Switches

The carrier injection in high gain semi-insulating GaAs photoconductive semiconductor switches (PCSS) is studied. A great quantity of carrier generation in the insulating region of the GaAs PCSS depends upon photo-ionization and impact ionization. The impact ionization avalanche carrier generation exists in the electron avalanche domains (EAD). The EAD is closely related to the growing domains associated with carrier injection. Carriers are injected either at the contacts (Cathode and Anode) or at the tip of the current filaments which works as a “contact reaching further into the gap”. Carrier injection plays an important role for the EAD formation.

Spontaneous Radiation Energy of Current Filaments in GaAs Photoconductive Semiconductor Switches

The spontaneous radiation energy of the current filaments in high gain GaAs photoconductive semiconductor switches (PCSS) is quantificationally analyzed. The spontaneous radiation formula of the current filaments was derived. The concept of the distribution function of the radiation intensity dependent on radiation wavelength was first introduced in GaAs samples. The radiative recombination coefficients of four peak wavelengths were estimated by the statistical-physical method in high gain GaAs PCSS. Calculated according to the radiative recombination coefficient of 890 nm radiation, the spontaneous radiation energies are consistent with the experimental observations. This explains the observations about optical output energy versus filament current.

高增益砷化镓光导开关中的特征量分析

高增益砷化镓光导开关中的特征量分析

Longevity of optically activated, high gain GaAs photoconductive semiconductor switches

The longevity of high gain GaAs photoconductive semiconductor switches (PCSSs) has been extended to well over ten million pulses by reducing the density of carriers at the semiconductor to metal interface. This was achieved by reducing the density in the vertical and lateral directions. The latter was achieved by varying the spatial distribution of the trigger light thereby widening the current filaments that are characteristic of the high gain switches. We reduced the carrier density in the vertical direction by using ion implantation. These results were obtained for currents of about 10 A, current duration of 3.5 ns, and switched voltage of /spl sim/2 kV. At currents of /spl sim/70 A, the switches last for 0.6 million pulses. In order to improve the performance at high currents, new processes such as deep diffusion and epitaxial growth of contacts are being pursued. To guide this effort we recorded open shutter, infra-red images, and time-resolved Schlieren images of the current filaments, which form during high gain switching. We measured, under varying conditions, a carrier (electrons or holes) density that ranges from 3/spl times/10/sup 17/ cm/sup -3/ to 6/spl times/10/sup 18/ cm/sup -3/.