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系统研究了在调制掺杂AlGaAs/GaAs异质结中嵌入InAs量子点后对二维电子气输运特性的影响。使用分子束外延设备生长了量子点层与二维电子气沟道距离(Tch)不同的3个样品,霍尔测试结果表明,二维电子气的电子迁移率和载流子浓度都随Tch的减小而降低。基于几何相位分析算法对部分样品的高分辨透射电镜图像进行了处理,得到了其应变分布图。结果表明,应变主要分布在量子点的周围,并延伸到了量子点的上方。该不均匀的应力场可能是除库伦散射外影响电子迁移率降低的另一个重要因素。
The influence of InAs quantum dots embedded in modulation-doped AlGaAs / GaAs heterojunction on the transport properties of two-dimensional electron gas has been studied systematically. Three samples with different quantum dot layers and two-dimensional electron gas channel distances (Tch) were grown by molecular beam epitaxy. The Hall test results show that the electron mobility and the carrier concentration of two-dimensional electron gas both increase with the increase of Tch Reduce and reduce. Based on the geometric phase analysis algorithm, the high resolution TEM images of some samples were processed and their strain distributions were obtained. The results show that the strain is mainly distributed around the quantum dots and extends above the quantum dots. This inhomogeneous stress field may be another important factor that affects the reduction of electron mobility in addition to the Coulomb scattering.