Characteristics of GaAs PCSS triggered by 1 μJ laser diode

Abstract

Various kinds of switches exhibit significant function in the field of pulse power. Among them Photoconductive Semiconductor Switch (PCSS) stands out because of its numerous advantages, such as low time jitter, fast response, high repetition rate, compact size, easy integration and so on. Laser Diode (LD) is small in size, low-cost and can be easily integrated compared with traditional laser devices. Waveguide tube is a kind of laser transmission device. By using LDs which emits laser pulse with a dominant wavelength of 905 nm and a waveguide tube, three different shapes of laser spot are obtained to trigger a semi-insulating GaAs PCSS which has vertical structure. Laser energy and laser power are fixed to 1 μJ and 33.3 W separately. As the illuminating area on the PCSS differs with different shapes of laser spot, the influences of average trigger energy per unit area to the output characteristics of the PCSS are studied. The experiment results demonstrate that not only the total trigger energy but also the energy density influences the characteristics of PCSS. This paper presents related experiment results, and some further discussions are given.

Effects of spot size on the operation mode of GaAs photoconductive semiconductor switch employing extrinsic photoconductivity

“…For the GaAs PCSS operating in the nonlinear mode, as reported in [17], compared to the long-striped spot perpendicular to the current channel, the focused spot with a narrower spot width can induce a higher nonlinear-mode output. Additionally, similar to the results presented in reference [16], our results demonstrate that the line-shaped spot across the electrodes and the spot covering the whole switching area are more effective for inducing a higher output than the point spot or partial line-shaped spot.…”

“…Some studies have pointed out that the photoelectric conversion efficiency of linear PCSS can be significantly improved by adopting the illuminating spot with the appropriate profile or location [15,16]. In addition, some typical illuminating spots with specific shapes have also been designed to characterize the influence of the spots on the photoelectric threshold and triggering efficiency of the PCSS operating in the nonlinear mode [17,18].…”

Photoexcited carrier dynamics in a GaAs photoconductive switch under nJ excitation

“…The most attractive feature of GaAs PCSSs is the process of photoexcited carrier multiplication by impact ionization after the removal of external optical excitation, which results in a reduction of the required optical excitation energy. This avalanche operation is known as the high gain (HG) or nonlinear mode, even if optical energy on the scale of microjoules (μJ) or nanojoules (nJ) is employed [11][12][13][14].…”

Roles of voltage in semi-insulating GaAs photoconductive semiconductor switch

“…While demonstrating apparent gain with high voltage, the switch runs in lock-on state. [4][5][6] The low leakage current resulting from the high dark resistivity of SI GaAs ensures that high-gain PCSS is capable of sustaining higher electric field before breaking down. [7][8][9] Conversely, the increase in leakage current at high voltage can degrade the high resistivity of PCSS, [7] and then the lifetime, [10] which is one of the important issues for highgain PCSS.…”