Theory of interface roughness scattering in quantum wells

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Abstract
Interface roughness strongly influences the transport properties of thin quantum wells. The commonly used model of interface roughness scattering approximates the well potential by infinitely high barriers. By using SiGe as an example, we demonstrate that this approximation strongly overestimates interface roughness scattering for narrow quantum wells. Our calculations show that the low-temperature mobilities of two-dimensional hole gases in SiGe and of electrons in strained Si quantum wells are limited by interface roughness scattering for well widths below 20-50 Å. The discussed effect of finite barrier heights on carrier scattering should be considered in transport investigations of materials such as GaAs/AlGaAs and Si/SiGe, when the well width is in the range of 100 Å or below.
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