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采用有限元分析方法(FEM)求解泊松方程,连续性方程,以及热传导方程对AlGaN/GaN高电子迁移率晶体管的自加热效应进行了数值模拟研究。着重比较了晶体管在SiC、Si及蓝宝石衬底上的沟道温度和漏电流。同时讨论了在外延层和衬底接触处的热边界电阻对晶体管电行为的影响。数值模拟表明,由于SiC的热导比较大,晶体管在其衬底上有较大的漏电流和较低的沟道温度,热边界电阻对其电行为有比较大的影响。相反,由于蓝宝石的热导比较小,晶体管在其衬底上有较低的漏电流和较高的沟道温度,显现出了比较大的自加热效应,热边界电阻对其电行为的影响可以忽略。
The finite element method (FEM) is used to solve Poisson equation, continuity equation and heat conduction equation to simulate the self-heating effect of AlGaN / GaN high electron mobility transistor. The channel temperature and leakage current of transistors on SiC, Si and sapphire substrates are compared. The influence of the thermal boundary resistance at the contact between the epitaxial layer and the substrate on the electrical behavior of the transistor is also discussed. The numerical simulation shows that the transistor has larger leakage current and lower channel temperature on its substrate due to the larger thermal conductivity of SiC, and the thermal boundary resistance has a greater influence on the electrical behavior. In contrast, due to the relatively small thermal conductivity of sapphire, transistors have lower leakage current and higher channel temperature on their substrates, exhibiting a relatively large self-heating effect, and the effect of thermal boundary resistance on their electrical behavior can be ignore.