Design of a lateral photoconductive semiconductor switch with a low resistivity region on semi-insulating GaN to enhance breakdown characteristics

Abstract

The breakdown characteristics of the semi-insulating lateral GaN photoconductive semiconductor switches (PCSS) with low resistivity region (LRR) structure were simulated. The design, which can reduce the peak electric field by adjusting the electric field distribution for PCSS, was first proposed. In comparison to conventional field plate and n-type doping below the electrode structures, the LRR structure robustly enhances the breakdown characteristics of PCSS while reducing the influence of on-state characteristics. The impact of different structural parameters on the breakdown voltage and on-state characteristics was investigated. In the case of a small size device with a 5 μm electrode gap, the LRR structure is able to decrease the peak electric field by 54 % at 400 kV/cm and increase breakdown voltage by 45 %. When the electrode gap is increased to 0.25 mm, under a bias voltage of 5 kV, the field plate structure can reduce the peak electric field by 35 %, but the LRR structure can reduce the peak electric field by 42 %. When applied a voltage of 2 kV, the PCSS with the LRR structure triggered by a laser pulse with a wavelength of 532 nm and an energy of 265 μJ has a minimum on-resistivity being less than 0.5 Ω cm and the resistivity ratio between the off and on states reaching up to 1 × 108.