Improved Photocurrent for Gallium Nitride Photoconductive Semiconductor Switch by SiO2 Anti-Reflection and (SiO2|Ta2O5)6 High-Reflection Dielectric Films

A new absorption technique is proposed in this research for gallium nitride (GaN) photoconductive semiconductor switches (PCSSs) by using anti-reflection and high-reflection dielectric films. The films have dual functions of enhanced optical absorption and dielectric passivation for the device. The experimental results show that the reflectivity of SiO2 anti-reflection film is 0.67%, and the transmissivity of (
${\mathrm{SiO}}_{{2}}\vert $
Ta2O5)6 high-reflection film is 3.2%. Besides, their breakdown electric fields are 3.89 MV/cm and 2.82 MV/cm, respectively. At 93.75 kV/cm, a wavelength of 532 nm, and an energy of
$90~\mu \text{J}$
result in a photocurrent of 1.2 A with the presence of the film, which is 73.4% higher than that of a traditional device. Furthermore, we can adjust the thickness of the film to obtain a wider range of wavelength absorption, and our technique can also be used employed for PCSSs with weak optical absorption, such as SiC.