Self-heating effects of picosecond optoelectronic switches based on vertical high-voltage structures with p-n-junctions (VPSS) operating in a high-frequency mode were theoretically studied for the first time. It is shown that strong temperature dependence of the control radiation absorption coefficient k(T) is the main factor determining the maximum switching frequency fmax and the corresponding maximum crystal temperature Tmax, as well as distributions of temperature T and current density j over a device area. A two-dimensional analysis of the simplest electrothermal model of VPSS embedded into a double coaxial forming line showed that an increase in the switching frequency f leads to displacement of current to device periphery, where the temperature is minimal. However, distributions of T and j over the device area remain stable if f<fmax and T<Tmax. Of course, the values fmax and Tmax depend on the energy of control radiation pulses, pulse switching power and heat sink conditions. For VPSS based on nondirect-gap semiconductors (Si, SiC), they varies within 20-120 kHz and 120-160 oC, quite sufficient for practical application. However, VPSS based on direct-gap semiconductors (GaAs, InP) are not actually suitable for operation in high-frequency modes due to too sharp dependence k(T).
@article{arxiv.1806.06922,
title = {Power Nano- and Picosecond Optoelectronic Switches Based on High-Voltage Silicon Structures with p-n Junctions III. Self-heating effects},
author = {A. S. Kyuregyan},
journal= {arXiv preprint arXiv:1806.06922},
year = {2019}
}