Study On GaN-based HEMT Device Performance And Optimization Of Design

GaN is a tipical example of the third-generation semiconductor materials which rapid rise in the high-temperature, high-frequency, high-power microwave fields. It is a wide bandgap semiconductor materials which has high thermal conductivity, high breakdown field strength, high electron drift velocity, high temperature resistance,corrosion resistance and stable chemical properties. Compared with previous generations of semiconductor materials, such as Si and AsGa, the excellent performance of GaN prompt it wide used in high-temperature, high-frequency high-power microwave and photoelectron fields.Firstly, the work introduced the research status and the development history of AlGaN / Ga N HEMT at home and abroad, the properties and characteristics of GaN material is be Summarized, and the structure and principle of AlGaN / GaN HEMT is described systematically. Then, the unique polarization effects and two-dimensional electron gas of AlGaN / GaN heterostructure is be described distinctly, and their existence principle were studied. The core of this work is estabilish modle of AlGaN/GaN HEMT device by ATLAS software, the simulation of AlGaN / GaN HEMT is studied by change the parameters of gate-drain spacing, gate length, etc and change the structure of field plate and substrate reasonably. The results of the simulation show the relationship between performance of AlGaN / GaN HEMT device and gate-drain spacing, gate length, field plate structure, substrate material, selfheating effect etc, and the optimization of device design is got by discussing and analyzing the result in-depth.The final results showed that: reduce the gate length is conducive to reduce the threshold voltage of the device, increase the drain current of the device, and improve the transfer characteristics and I-V characteristics of the device; the equivalent resistance of the device is impact by gate-drain spacing directly, in the Linear region, if the gate-drain spacing is increased, the drain current is reduced, but gate-drain spacing does not affect the threshold voltage and saturation current, and field plate structure can reduce the drain current of the device, increase the breakdown voltage and restrict current collapse effectively; the selfheating of spphire subsrate is more serious than the substrate consisting of Si and diamond; the thickness of Si layer reduced is helpful to reduce device self-heating effect and the maximum temperature of active region in the substrate consisting of Si and diamond.Since the study of GaN-based HEMT is not yet mature, the problem of the device performance degradation and failure caused by self-heating effect and current collapse effect is not solved, thus, the method of changing the device parameters size to optimize the design of the GaN-based HEMT devices was studied to improve the device performance.