Sub-Bandgap Photoconductive High Voltage Switch of Mn:GaN Semiconductor

We demonstrate the high voltage switch based on a Mn-doped GaN semiconductor involving sub-bandgap photo-excitation by means of Nd:YAG laser emitting in the second harmonic. Induced bandtails of Mn were found to be photoconductive starting from the 700 nm wavelength threshold. Turn-on time of the high voltage switch was probed with short 10 ps duration laser pulses revealing the voltage pulse duration and rise time values can be as short as 1 ns and 100 ps, respectively. Relaxation of the switch photoconductivity exhibited a 2 ns decay time at low-intensity laser pulses, while at the highest intensities, it increased up to 14 ns value due to the saturation of the intermediate band or nonradiative defects. The resistance of on state was regulated up to ten orders of magnitude under the change of the laser pulse intensity, which allowed the switch to wire kilovolt voltage pulses on the load of
$50~\Omega $
impedance. The developed high-voltage switch with performance in nanosecond time scale is beneficial for applications where high repetition rate operation is required.