Improved Longevity and Reliability for Hundreds of Amps, Repetition Frequency Avalanche GaAs PCSS by High Thermal Conductivity Graphene Heat Sink

Abstract

The avalanche multiplication effect of carriers in gallium arsenide photoconductive semiconductor switch (GaAs PCSS) can generate a robust current, thereby amplifying the impact ionization and recombination of carriers while yielding a filament current with high density. The movement of carriers and phonons intensifies the thermal effect within the device, thus establishing a pernicious cycle that leads to substantial heat accumulation and eventual breakdown of the switch. This is precisely the predicament that PCSS urgently needs to address. Herein, a novel longevity-enhancing technique for GaAs PCSS is proposed, which is based on the laminates of graphene heat sinks (GHSs) and aluminum nitride ceramic substrates (AlN-CSs). The GHS has dual functions of improved heat dissipation and dielectric packaging for the device. The experimental results show that the GHS has excellent photoelectrothermal stability, with the dielectric constant and thermal conductivity reaching 13.3 and 500 W/(m $\cdot $ K), respectively. At 40 kV, a wavelength of 915 nm with 5 Hz, and an energy of $\sim 70~\mu $ J, a longevity of $2.7\times 10^{{4}}$ achieved with the presence of the GHS and AlN-CS, which is about 70% higher than that of a traditional device. Additionally, the photocurrent of hundreds of amps can be stably output simultaneously. Furthermore, our technique can also be employed for other high-power PCSSs and other power devices.