This paper is based on a comprehensive review of the literature and our own studies. We present a summary of the theoretical models and related empirical expressions to evaluate parameters related to the carrier transport within Si/SiGe heterostructures. The models and expressions include the effects of alloy composition and mechanical strain on the band structure of Si/SiGe alloys and the corresponding interfaces. They are presented in a form suitable for implementation in various types of device simulators. Important parameters, such as the band structure of strained or relaxed SiGe, the conduction and valence band offsets in the Si 1−x Ge x /Si 1−y Ge y heterostructures, the effective transport masses and the densities of states, have been calculated and shown to be in good agreement with existing experimental and theoretical results. Analytical expressions of those parameters as a function of Ge composition of the SiGe alloy have been given for strained Si on relaxed Si 1−y Ge y substrate and strained Si 1−x Ge x on Si substrate.

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In this paper we focus on the problem of interface roughness scattering which is treated non-perturbatively by incorporating the effects of scattering as a boundary condition for the Boltzmann transport equation. The scattering probability is derived and implemented in an ensemble Monte Carlo simulation of electron transport in relaxed and strained Si n-MOSFETs. We compare the internal device behaviour as a function of the interface quality between short channel relaxed and strained Si n-MOSFETs. We provide further evidence that the strained Si/SiO 2 interface is less rough, requiring a longer correlation length and smaller rms height for the strained Si/SiO 2 interface. The high doping densities encountered necessitate the self-consistent use of degenerate (Fermi-Dirac) statistics.

It has been known for many years that interface roughness scattering, particularly off the Si/SiO2 interface, is a limiting factor in device performance of MOSFETs. This becomes increasingly important as gate lengths are shrunk to decanano dimensions along with the move towards SiGe hetero-technology. However, analysis of interface transport is hampered by the lack of detailed physical models, especially for surfaces where intercalation occurs. This paper presents an efficient method for following the motion of wave-packets scattering off a rough interface. We are also able to calculated directly ab-initio interface scattering rates for use in Monte Carlo simulations.

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