Fundamental Trade-Off Between the Operating Frequency and Output Power Density in Linear-Mode Modulated SiC Photoconductive Switch

Due to insufficient carrier concentration in conventional radio frequency (RF) devices, there is a trade-off between the operating frequency and output power. While if photocarriers are generated through modulated light irradiation inside the bulk material, photoconductive semi-conductor switches (PCSS) might break through the limitation of carrier concentration and can generate modulated microwave signals that balance high power and high frequency. This article discussed a possible trade-off between operating frequency and output power density that similarly occurs in vanadium compensated semi-insulation (VCSI) 4H-SiC PCSS. Through finite element analysis, two methods of changing electrode gap and V concentration were proposed to select device design schemes under specific frequency and output power requirements. At the V concentration of 2.3 × 10
¹⁷
cm
⁻³
, the device can output microwave signals with a peak output power density of approximately 219 kW/mm at a 20 kV bias voltage.