用于SiC和蓝宝石衬底的AlGaN/GaN HEMT热解析模型

Thermal Analytical Model for AlGaN/GaN HEMT for SiC and Sapphire Substrate

研究了温度的升高对低场迁移率及阈值电压的影响,建立了模拟AlGaN/GaN HEMT直流I-V特性的热解析模型。模型考虑了极化、材料热导率、电子迁移率、薄层载流子浓度、饱和电子漂移速度及导带断续的影响。模拟结果表明,低场迁移率随温度的升高而下降,阈值电压随温度的升高略有增加,但变化很小,而沟道温度随漏压的增加上升很快,并最终导致输出漏电流的下降。最后将模拟结果与实验值进行对比,符合较好,证明了该模型的正确性,并可以应用于SiC和蓝宝石两种不同衬底AlGaN/GaN HEMT器件的模拟。

The effects of elevated temperatures on low-field mobility and threshold voltage were investigated. A temperature dependent analytical model was presented for AlGaN/GaN HEMT to simulate the DC I-V performance. In this model the effects of polarization, material thermal conductivity, electron mobility, sheet carrier density, velocity saturation and conduct band discontinuity were taken into consideration. The simulated resuIts show that low field mobility decreases, whereas threshold voltage slightly increases with the increment of temperature, channel temperature rises greatly with the increase of drain voltage and results in the decrease of drain current. The comparison between simulations and measurements shows a good agreement, it proves that this model is accurate and can simulate the DC I-V performance of AlGaN/GaN HEMT for SiC and sapphire substrate.