Photonic Interactions with Semiconducting Barrier Discharges
Semiconducting Barrier Discharges (SeBDs) generate uniform ionization waves in air at atmospheric pressure. In this work, we investigate how externally applied irradiation synchronized with the discharge can mimic photoconductive-type coupling between the plasma and the semiconductor surface. By illuminating the Si-SiO$_2$ interface with nanosecond pulsed irradiation at wavelengths from 532 nm to 1064 nm, and using fast imaging, optical emission spectroscopy, and current-voltage measurements, we demonstrate that the photoexcitation of charge carriers in silicon enhances the plasma emission and increases the reduced electric field, with no detectable change in the electrical energy. The magnitude and thresholds of these responses depend on wavelength. By comparing the SeBD to a MOS photodetector, this behaviour can be explained by the absorption length. This length determines whether carriers are photogenerated inside the depletion region at the SiO$_2$-Si interface, where they are efficiently separated and undergo impact-ionization amplification, or deeper in the silicon bulk where carrier separation is weaker and free-carrier absorption diminishes the quantum efficiency. These results focus on the microscopic processes governing the plasma-semiconductor coupling and demonstrate how the optoelectronic properties of silicon can influence surface ionization waves.