高迁移率低密度碳掺杂（100）GaAs二维空穴系统的散射机制
Scattering Mechanisms in a High Mobility Low Density Carbon-Doped (100) GaAs Two-Dimensional Hole System
摘要：
本文系统地研究了低密度掺碳（100）GaAs二维空穴系统（2DHS）中迁移率的密度依赖性。在T= 50 mK时，测得密度p=6.2 x 10^10 cm^-时的迁移率为2.6 x 10^6 cm ^2/Vs。这是迄今为止报告的2DHS的最高移动性。使用背栅样品几何结构，研究了迁移率在2.8 x 10^10 cm^-2至1 x 10^11 cm^-2范围内的密度依赖性。使用单个指数α，迁移率对密度不能拟合为形式μ ~ p^α的幂律依赖性。我们的数据表明，一个连续的演变的幂律与α范围从~ 0.7在高密度和增加到~ 1.7在最低密度测量。具体到我们的结构的计算表明，从均匀的背景杂质散射在高密度的远程电离杂质散射在低密度的主导散射机制的交叉。这是第一次观察到的载流子密度诱导的过渡，从背景杂质为主的远程掺杂剂为主的运输在一个单一的样品。
英文摘要：
We report on a systematic study of the density dependence of mobility in a low-density Carbon-doped (100) GaAs two-dimensional hole system (2DHS). At T= 50 mK, a mobility of 2.6 x 10^6 cm^2/Vs at a density p=6.2 x 10^10 cm^- was measured. This is the highest mobility reported for a 2DHS to date. Using a back-gated sample geometry, the density dependence of mobility was studied from 2.8 x 10^10 cm^-2 to 1 x 10^11 cm^-2. The mobility vs. density cannot be fit to a power law dependence of the form mu ~ p^alpha using a single exponent alpha. Our data indicate a continuous evolution of the power law with alpha ranging from ~ 0.7 at high density and increasing to ~ 1.7 at the lowest densities measured. Calculations specific to our structure indicate a crossover of the dominant scattering mechanism from uniform background impurity scattering at high density to remote ionized impurity scattering at low densities. This is the first observation of a carrier density-induced transition from background impurity dominated to remote dopant dominated transport in a single sample.
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