Reducing Dark-State Current for GaAs Photoconductive Semiconductor Switch by Ultrafine Grinding Process

With unique characteristics, especially the simultaneous combination of high-power capacity and high repetition frequency, gallium arsenide photoconductive semiconductor switches (GaAs PCSS) have a wide range of applications in the field of pulsed power technology. In view of the ever-shrinking device area and the ever-increasing operating voltage of GaAs PCSS, its sidewall morphology has become more and more obvious on the lifetime and reliability of the device. To address this issue, this article comparatively investigates the influence of GaAs PCSS sidewall morphology on the electrical characteristics of the devices. The results show that the grinding process is favorable to improve the quality of the device sidewalls, so as to achieve the purpose of improving the life and reliability of the device. The leakage current of grinded-GaAs PCSS (G-GaAs PCSS) is reduced to
$11.43~\mu \text{A}$
(average value) at a bias voltage of 45 kV, which is more than five times lower than that of the ungrinded-GaAs PCSS (U-GaAs PCSS). Notably, the G-GaAs PCSS enters the nonlinear mode with a lower threshold electric field and a high
${I}_{\text {light}}/{I}_{\text {dark}}$
ratio (
$1.45\times 10^{{7}}{)}$
. The microscopic morphology of the two devices was also experimentally analyzed, and the improvement in the electrical characteristics of the G-GaAs PCSS was attributed to the improvement of the sidewall quality of the device by the grinding process.