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研究了非故意掺杂(UID)与半绝缘(SI)GaN缓冲层(BL)上的Al0.35Ga0.65N/GaN异质结构高温下的电子输运特性,应用Hall效应系统地测量了样品在高温下的电子面密度和电子迁移率随温度变化的关系.实验发现,高温下AlGaN/GaN异质结构的电子迁移率主要受到LO声子散射的作用,其中,UID-BL样品的电子面密度随温度升高而逐渐上升,SI-BL样品的电子面密度则随温度升高呈现先下降再平衡后上升的规律.对相应的未生长AlGaN势垒层的本征GaN薄膜的高温电阻特性分析表明,随着温度的升高,UID-BL样品的电子迁移率受到背景载流子的影响逐渐增大;SI-BL样品的电子迁移率在室温附近受附加位错散射的影响较大,600K以后受背景载流子的影响缓慢增强,这对于研究AlGaN/GaN异质结构器件的高温特性具有很好的参考意义.另外,由理论计算可知,高温下二维电子气(2DEG)逐渐向势垒层和缓冲层内部扩展,电子在第一子带的占据从室温下的86%下降到700K时的81%.
The electron transport properties of Al0.35Ga0.65N / GaN heterostructures on unintentionally doped (UID) and semi-insulating (SI) GaN buffer layers (BL) were investigated at high temperatures. The Hall effect was used to systematically measure the electron transport It is found that the electron mobility of AlGaN / GaN heterostructures at high temperature is mainly affected by the LO phonon scattering, in which the electron density of UID-BL samples With the increase of temperature, the electronic surface density of SI-BL samples first decreases and then rebalances and then increases.The analysis of the high-temperature resistivity of the intrinsic GaN film of the un-grown AlGaN barrier layer The results show that the electron mobility of UID-BL samples increases with the background charge carriers as the temperature increases. The electron mobility of SI-BL samples is greatly affected by additional dislocation scattering near room temperature, Which is a good reference for the study of the high temperature characteristics of AlGaN / GaN heterostructured devices.Furthermore, theoretical calculations show that the 2DEG gradually increases in potential Base layer and buffer layer internal expansion, electricity 81% of the time occupied by the first sub-band decreased from 86% at room temperature to 700K.