Photoexcited carrier dynamics in a GaAs photoconductive switch under nJ excitation

Abstract

The bunching transport of photoexcited carriers in an GaAs photoconductive semiconductor switch (PCSS) with interdigitated electrodes is investigated under the femtosecond laser excitation. The continuous outputs featured with high-gain (HG) characteristic are obtained at single-shot and 1-kHz by varying the optical excitation energy. An ensemble three-valley Monte Carlo simulation is utilized to investigate the transient characteristics and the dynamic process of photoexcited carriers. It demonstrates that the presence of plasma channel can be attributed to the bunching of high-density electron-hole pairs, which transports in the form of the high-density filamentary current. Results provide the pictures of the evolution of photoexcited carriers during the transient switching. The photoinduced heat effect is analyzed that reveals the relative failure mechanism at optical excitation at repetition rates.

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

“…Operating in this mode, the switch presents the characteristics of lower jitter and long lifetime, but usually needs the ~ mJ level laser energy for the high power output. Compared to the linear mode, the PCSS in the nonlinear mode can remain in the turn-on state after the laser is extinguished, making the output pulse width reach tens of nanoseconds, or even hundreds of nanoseconds and above [8][9][10]. The switch operating in this mode features the avalanche multiplication of carriers.…”

“…Almost all existing researches indicate that the illuminating spot significantly affects the development of operation mode, further determining the on-state performances of PCSS. However, despite these efforts, the influencing mechanism of the spot size on the operation mode of GaAs PCSS is still unclear, especially when the PCSS employs the extrinsic photoconductivity, generally introducing the optical absorption depth of several millimeters and evoking the complex switching transient [9,19]. Furthermore, to take full advantage of the illuminating laser and switch material, further investigating the influencing mechanism to optimize the illuminating spot and improve the on-state performances of GaAs PCSS is of considerable practical significance.…”

Metal Nanoparticles Assisted Ultrafast Laser Plasmonic Microwelding of Oxide–Semiconductor Interconnects

“…[1][2][3][4] While semiconductor materials as main functional units with controllable carriers transport are widely used in micro/nano optoelectronics. [5][6][7] By combining to maximize the advantages of both materials, integration of semiconductor and oxide has drawn considerable attention. For example, the wafer-level bonded Sapphire-Si heterogeneous structures have shown great potential in spatiotemporal tailoring of laser beam, ultrafast laser has been successfully used in heterogeneous materials microwelding such as Cu-Si, [22] Si-GaAs, [23] and alumina-YSZ.…”