The Study On THz GaN IMPATT Diode

Terahertz technology exhibits great potential for wide applications, such as astronomy, physics, biology, hylology, communication, national secudty and military. Terahertz sources is the fundametal of the all Practical applications. There is still lack of low-cost, portable and high output power THz source. In this background, we got a in-depth research on IMPATT diode with new material GaN. We designed several kinds of GaN IMPATT diodes and carried out a detailed simulation analysis. And discuss the device performance at different temperature conditions or with a heterojunction. The main research work and results are as follows:1. We study the working mechanism of IMPATT diode and build simulation model. Combine the avalanche,transit-time characteristics and drift-diffuse model on carriers, build simulation model by the device emulator ATLAS.2. We designed three kind of GaN IMPATT structure devices, and research the performance separately. The three structure are high-low-high single-drift region type, common single-drift region type and double-drift regions type. The optimum working frequency is 0.46THz,0.16THz,0.31THz separately. And the RF output power density is 13.8mW/?m2,12.6 mW/?m2,22.6mW/?m2 separately. Assuming that the area of the device is 100?m2, the RF output power is more than 1 W in single-drift region type IMPATT, and the RF output power is more than 2W in double-drift regions type IMPATT.3. With the new experimental reported data and Monte Carlo simulation data on GaN and AlGaN materials, we get the GaN and AlGaN mobility-field models at different temperature. And research the temperature characteristic of GaN IMPATT with these models. The study shows that the DC to RF conversion efficiency will reduce when temperature increase. Howerer, the influence on RF output power is small when temperature increase. The reason is breakdown voltage increase when temperature increase.4. Research on the GaN heterojunction IMPATT diode, design a kind of two sections single-drift region heterojunction IMPATT structure. The DC to RF conversion efficiency will increase and the working frequency will not decrease in this structure.5. The power-frequency effect and temperature effect exist in IMPATT was studied. And we discuss the device produce influenced by GaN technics condition, like p type doping and ohmic contact in GaN.Above all, the study on the GaN IMPATT from the theory and simulation is present. The simulation result shows that the GaN IMPATT can used in high power output, high temperature condition as semiconductor solid-state devices in THz. And build a foundation for GaN IMPATT diode production.