Response characteristic of femtosecond LT-GaAs photoconductive switches at different voltage biases

Abstract

The response characteristic of a femtosecond low temperature GaAs (LT-GaAs) photoconductive switch formed in a coplanar waveguide at different voltage biases is studied with the femtosecond photocurrent autocorrelation measurement technique. The experimental results show that the switching time increases when the bias voltage is increased from 103 to 105 V cm−1. We provide a physical model, combining the potential barrier lowering (the Frenkel–Poole effect) and the field-enhanced thermal ionization, to give a complete explanation to the response characteristic of the LT-GaAs photoconductive switch at larger varying bias fields ranging from 103 to 105 V cm−1.