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AlGaN/GaN结构中Al组分对2DEG迁移率有显著的影响,但对这种现象的机理分析非常欠缺,尚不清楚.结合最近研究的实验数据,采用多种散射机制联合作用的解析模型对变Al组分AlGaN/GaN结构中的二维电子气迁移率做了理论计算和分析,所考虑的散射机制包括声学形变势散射、声学波压电散射、极性光学声子散射、合金无序散射、界面粗糙散射、位错散射、调制掺杂远程散射等.发现势垒层Al组分增加引起的2DEG密度增大是造成各种散射作用发生变化的主要因素.77K下2DEG迁移率随Al组分的变化主要是由界面粗糙散射和合金无序散射决定,室温下这种变化则主要由极性光学声子散射和界面粗糙散射决定.计算的界面粗糙度参数与势垒层Al组分的函数关系说明,Al组分增大所造成的应力引起AlGaN/GaN界面粗糙度增大,是界面粗糙散射限制高Al异质结2DEG迁移率的一个重要因素.
The Al composition in AlGaN / GaN has a significant effect on the mobility of 2DEG, but the mechanism analysis of this phenomenon is very scarce and not clear.According to the experimental data of recent studies, the analytical model of the combined effects of various scattering mechanisms The theoretical calculation and analysis of the two-dimensional electron gas mobility in the Al-AlGaN / GaN structure have been done. The scattering mechanisms considered include acoustic deformation potential scattering, acoustic wave piezoelectric scattering, polar optical phonon scattering, Scattering, rough interface scattering, dislocation scattering, modulation-doped remote scattering, etc. It is found that the increase of the density of 2DEG caused by the increase of the Al component in the barrier layer is the main factor causing the various scattering effects to change. The change of the composition is mainly determined by the interface roughness scattering and the alloy disorder scattering, which is mainly determined by the polaroptical phonon scattering and the interface roughness scattering at room temperature.Compared with the Al layer Shows that the stress caused by the increase of Al composition increases the roughness of AlGaN / GaN interface, which is an important factor that restricts the mobility of high-Al heterojunction 2DEG due to interface rough scattering.