Semiconductor physics

Spatial inhomogeneity of impact-ionization switching process in power $\mathrm{Si}$ diode

S. K. Lyubutin^a, V. E. Patrakov^ab, S. N. Rukin^a, B. G. Slovikovsky^a, S. N. Tsyranov<sup>a

a</sup> Institute of Electrophysics, Ural Branch, Russian Academy of Sciences, 620016 Yekaterinburg, Russia
^b Ural Federal University named after the First President of Russia B. N. Yeltsin, 620002 Yekaterinburg, Russia

Abstract: Voltage drop process in power $\mathrm{Si}$ diode switched to a conducting state by an impact-ionization wave, which is excited by overvoltage pulse with a subnanosecond rise time, has been investigated. In experiments, a reverse voltage pulse was applied to a diode with a diameter of $6$ mm without preliminary reverse bias, which provided the average rate of voltage rise across the diode dU/dt in the range of $1$–$10$ kV/ns. Numerical simulations showed that calculated and experimentally observed voltage waveforms are in good quantitative agreement in the case when an active area of the structure $S_a$, through which a switching current flows, increases with $dU/dt$ value increasing. It was shown that at $dU/dt < 2$ kV/ns the active area tends to zero, and at $dU/dt > 10$ kV/ns it approaches the total area of the structure. Comparison with the results of similar studies shows that the increase in the active area of the structure with the increase in the $S_a$ value does not depend on the material of the structure (silicon and gallium arsenide), the number of layers in the semiconductor structure (diodes and thyristors), and also on the value of the initial bias voltage.

Keywords: impact ionisation, voltage rise rate, active area, switching time.

Received: 17.04.2023
Revised: 03.07.2023
Accepted: 02.10.2023

DOI: 10.61011/FTP.2023.07.56836.4871

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