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Previous: 4.2.3 Substrate Orientation (111) Up: Dissertation Enzo Ungersboeck Next: 5.1 Mobility |
Carrier mobility is a key parameter for the numerical simulation of the electrical characteristics of semiconductor devices. Many analytical models have been developed capturing accurately the dependence of mobility on temperature, doping, and electric field [Lombardi88,Selberherr89,Agostinelli91,Shirahata92,Darwish97,Kondo01,Reggiani02]. All these models were originally developed for unstrained Si. To describe the mobility in strained Si they have to be adapted accordingly [Dhar05].
In this work the electron mobility in bulk Si and Si inversion layers is analyzed by solving the semi-classical Boltzmann transport equation. The latter is solved numerically using a Monte Carlo (MC) method. For this purpose the Vienna Monte Carlo simulator VMC [VMC2.006] was developed, offering simulation algorithms for both bulk semiconductors and one-dimensional devices with models based on both analytical bands (ABMC) and the fullband structure (FBMC). VMC provides a comprehensive set of scattering models including phonon scattering, ionized impurity scattering, alloy scattering, and impact ionization.
The chapter is organized as follows: In Section 5.1, the basic features of the carrier mobility in semiconductors and the concept of the universality of the effective mobility are described. In Section 5.2 the validity of the Boltzmann transport equation as a fundamental equation for the description of carrier transport in semiconductor devices is discussed. The simulation method and an overview of the scattering models are given in Section 5.3. Finally, a new MC algorithm, which allows the inclusion of degeneracy effects, is presented in Section 5.4.
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Previous: 4.2.3 Substrate Orientation (111) Up: Dissertation Enzo Ungersboeck Next: 5.1 Mobility |