Transient and steady state simulations of internal temperature profiles in high-power semi-insulating GaAs photoconductive switches

Abstract

Simulations have been performed to determine the internal temperature profiles of high-power GaAs photoconductive switches in the presence of a current filament. No thermal instability is predicted below a power generation density level of about 1.3×1014 W/m3. This prediction is in keeping with recent experimental data on photoconductive semiconductor switch devices. It is shown that this power dissipation density threshold for stability exists under both dc and transient conditions. A simple model provides qualitative support for the power density threshold, and an explanation of the filamentary current radii that have been observed experimentally.

Picosecond Joule heating in photoconductive switch electrodes

“…9 A limited number of studies were devoted to the power dissipation and thermal behavior of PCSs. [10][11][12][13][14] These typically focus on high-power devices, where peak powers being switched commonly amount to on the order of several megawatts and therefore pose significant thermal management challenges to the overall system. Steadystate models are available to estimate the heat-sink area required to maintain the semiconductor below a given target temperature.…”

“…10 Transient analyses have studied the power wave form during switching 11 and thermal runaway failures attributed to current filamentation. [12][13][14] Due to their larger electrical and thermal masses, characteristic switch times and thermal time constants of high-power PCSs are on the order of 50 ns and 1 μs, respectively. 13 Microscale, low-power devices will exhibit dynamics that are several orders of magnitude faster.…”

“…[12][13][14] Due to their larger electrical and thermal masses, characteristic switch times and thermal time constants of high-power PCSs are on the order of 50 ns and 1 μs, respectively. 13 Microscale, low-power devices will exhibit dynamics that are several orders of magnitude faster. In addition, they offer an interesting potential to study picosecond thermal dynamics in other electronic and thermoelectric integrated devices.…”

Density-Dependent Effects on Pulse Compression in GaN Photodetectors Probed by Monte Carlo Studies

“…Historically, Auston was the first to suggest and probe such photoconductive applications [5]. Many such devices utilize light absorption of energy greater than their bandgap [6][7][8][9][10][11], the so-called extrinsic mode, using materials such as GaAs and lowtemperature grown gallium arsenide (LT-GaAs), InP, GaN, SiC materials, silicon on sapphire, etc. [12][13][14][15][16][17][18][19].…”

Lock-on physics in semi-insulating GaAs: Combination of trap-to-band impact ionization, moving electric fields and photon recycling

“…Photoconductive switching is of interest for various electronic applications in the pulsed power arena, [1][2][3][4][5][6][7][8] including microwave and millimeter wave generation, impulse and ultrawideband radar, particle accelerators, and directed energy systems. Advantages of optical switches include: (a) ultrafast response and turn-on times in the picosecond regime limited only by the characteristics of the optical trigger, (b) jitter-free response, (c) isolation between the electrical and optical systems, (d) superior repetitive rates, (e) higher-frequency response and controlled wave-shaping capability, (f) ability to scale to large voltages and currents in a single device without sacrificing speed, and (g) potential selectivity between multiple optical trigger signals based on the wavelength-dependent response of photoconductive switches.…”