Simulation Study Of GaN HEMT Hardened Structure With Single Event Irradiation

In recent years,a lot of research has been made on gallium nitride(GaN)material.As a typical representative of the third generation of semiconductor materials,devices made of GaN material have been widely used owing to its excellent performances.Although humans have made significant progress in the research of GaN materials,the superior properties of their materials have not been fully developed,there are still some problems with GaN devices,such as the concentration effect of the electric field near gate electrode,low breakdown voltage and anti-radiation hardening.In addition,there are relatively few studies on the anti-radiation of GaN devices,especially the research of methods for the hardness of devices.Therefore,this article focuses on the radiation-resistant hardened structure of GaN devices.It's expected to improve the single-event burnout(SEB)performances of the device without sacrificing the basic characteristics of the device,and to make the advantages of GaN are fully utilized.The basic structure in this article is the traditional structure with gate field-plate,two types of hardened structures are studied,and the main content is divided into two sections:In the first section,a hardened structure with an AlGaN interlayer is investigated.The interlayer acts as the back-barrier layer and reduces the leakage current of the buffer layer,thereby improving the breakdown voltage of the device.At the same time,due to the difference in the energy band,a new quantum well is introduced by the AlGaN interlayer.A lot of electrons induced by radiation are confined in the new quantum well and can't be injected into the conductive channel,so the number of electron-hole pairs induced by the impact ionization is reduced,thereby improving the SEB characteristics of the device.By optimizing the parameters with simulation software,the breakdown voltage and the SEB threshold voltage of the hardened structure are 828 V and 475 V,respectively,which increased by 56% and 70%,respectively,and the device's output characteristics is slightly decreased.In the second section,a hardened structure with Schottky metal contact is studied.First,a part of depletion region is formed near the Schottky metal,the leaked electrons are continuously recombined as they pass through the buffer layer containing high-concentration acceptor impurities,so the leakage current of the device is reduced and the breakdown voltage is increased.Secondly,a great number of electron-hole pairs are generated by the impact ionization and holes can be effectively extracted by the grounded Schottky metal electrode,which reduces the possibility of SEB for the device and significantly improves SEB characteristics.Simulation results show that the breakdown voltage of the hardened structure is doubled and the SEB threshold voltage reaches 1010 V,but the saturation current of the device is greatly reduced.