【摘要】 采用高温Hall测量仪对一个全应变和一个部分应变弛豫的AlGaN/GaN异质结构中2DEG的高温输运特性进行了研究,温度变化范围从室温到680K.研究结果表明:在高温段2DEG的迁移率主要受LO声子散射限制;在室温,异质界面处的非均匀压电极化场对2DEG迁移率的散射也是一个主要的散射机制.同时,计算结果显示,随着温度升高,更多的电子跃迁到更高的子带,在更高的子带,其波函数逐渐扩展到AlGaN层内部以及GaN体内更深的位置,导致LO声子散射的屏蔽效应减弱且来自AlGaN层内的合金无序散射增强.更多还原

【Abstract】 The transport properties of the two-dimensional electron gas（2DEG） in fully strained and a partially strain-relaxed Al_0.22Ga_0.78N/GaN heterostructures at temperatures ranging from 300 to 680K are investigated with Hall measurements.The results indicate that the 2DEG mobility is primarily limited by LO phonon scattering processes at high temperatures.The calculated results also show that the 2DEG distribution gradually expands to the inside of the AlGaN and GaN layers with increasing temperature due to the electron transfer to the higher order subbands.Hence,the effect of screening on LO phonon scattering is weakened and the alloy scattering of the AlGaN layer on the 2DEG becomes stronger.更多还原