Peculiar Transmission Characteristics of the Large Gap Semi-Insulating GaAs Photoconductive Switch

Unique experimental phenomena are discovered in a large gap semiinsulating (SI) GaAs photoconductive semiconductor switch (PCSS) and the peculiar transmission characteristics are exhibited in the experiment. The transmission characteristics for the large gap SI-GaAs PCSS are entirely different from the commonly designed PCSS. By analyzing the differences of the transmission characteristics between the common and the large gap SI-GaAs PCSS, a detailed statistical analysis and theoretical explanations are expounded. The large gap SI-GaAs PCSS works in the overvoltage relaxation limit space charge accumulation (LSA) mode when the conditions of 5×10⁴ s⋅cm⁻³ ≤ n₀/f ≤ 3×10⁵ s⋅cm⁻³ and n₀ L ≥ 10¹³ cm⁻² must be met in the switch, with n₀ being carrier concentration and f the frequency. The large gap SI-GaAs PCSS we developed has not shown the nonlinear (lock-in) behavior at high bias voltage, so the withstand voltage and service life for PCSS are improved.