| In recent years, with the terahertz (THz) technology developing rapidly, high-frequency and high-power terahertz sources gradually become a research hotspot. Currently the mostly used semiconductor solid-state power electronic devices in terahertz source are negative resistance devices, such as Gunn diodes, Resonant tunneling diodes (RTD), IMPATT Diode, etc. . During these diodes, Gunn diodes have the advantage of their high frequency, high stability, high reliability, low noise, broad bandwidth, low power supply voltage, and long working life, so Gunn diodes have a great potential in the terahertz application.Presently,GaAs-based, InP-based Gunn diodes already quite mature. Although these diodes have high reliability, low output powers of these devices limited their application greatly. The third generation semiconductor materials (such as SiC, GaN) have large band gap, high critical field strength, high thermal conductivity, high carrier saturation velocity and other excellent characteristics, so they have been widespread concern in the field of microwave and millimeter wave high-power electronic devices. The Monte Carlo simulation results of GaN materials show that, GaN-based negative resistance oscillation can be as large as 750GHz, far greater than the GaAs's 140GHz, and more importantly GaN-based devices with higher output power than GaAs-based one to two orders of magnitude in the terahertz band, the output power of these devices can reach several hundred milliwatts or even a few watts, which is the most interesting device performance in the terahertz field.In this paper, on the basis of the device's materials and processes, we developed the basic GaN Gunn diode design principles, and based on these principles we designed two types GaN Gunn diodes for the application of terahertz. Simulation results of these GaN Gunn diodes show that they can work in the 200GHz, much higher than GaAs Gunn diode's 75GHz. Based on the Notch GaN Gunn diode, we give a basic manufacturing process for GaN Gunn diodes. And at the end of this paper we developed a 500GHz GaN Gunn diode oscillator. The high-power and high-frequency characteristics of GaN Gunn diode show its great potential in the THz applications. |
