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A comprehensive quantum anisotropic transport model for holes is used to study silicon PMOS inversion layer transport under arbitrary stress. The results have shown that the hole band structure is dominated by 12 'wings,' where mechanical stress, as well as the vertical field under certain stress conditions, alter the energies of the few lowest hole subbands, changing the transport effective mass, density-of-states, and scattering rates, and thus affecting the mobility.

A microscopic scattering matrix method is used to examine electron transport in the collector and emitter space charge regions of silicon bipolar transistors with different base widths. Accurate drift-diffusion expressions are consistent with current and transit time simulations of the matrix process. The base distribution at the collector edge indicates that electron velocity exceeds thermal velocity in the zero-field region.

Studies of heterojunction transport, utilizing a Boltzmann equation solution, reveals that classical thermionic emission theory accurately describes the I-V property and discontinuity of the quasi-Fermi level definition at the interface. The current and quasi-Fermi level splitting agree well with bias. The distribution functions close to the heterojunction interface are non-Maxwellian.

A spectral method for solving the Boltzmann equation by the scattering matrix approach was presented. The algorithm can be used to simulate both bulk and device characteristics with arbitrary field profiles. The analysis showed thatnumerical nonorthogonal basis functions can be used for device simulation applications. However, nonorthogonal numerical basis functions do not allow the optimization of the coefficients.

A proposed method in the evaluation of the basic assumptions of macroscopic transport models is presented. Results show that the method is also applicable to more sophisticated models. Particularly, assuming temperature as scalar and drift energy as insignificant do not provide critical estimations of the device performance. Also, the estimation of an energy-dependent mobility breaks down near the channel-drain junction.

A comprehensive quantum anisotropic transport model for holes was used to study silicon PMOS inversion layer transport under arbitrary stress. The anisotropic band structures of bulk silicon and silicon under field confinement as a two-dimensional quantum gas are computed using the pseudopotential method and a six-band stress-dependent k.p Hamiltonian. Anisotropic scattering is included in the momentum-dependent scattering rate calculation. Mobility is obtained from the Kubo-Greenwood formula at low lateral field and from the fullband Monte Carlo simulation at high lateral field. Using these methods, a comprehensive study has been performed for both uniaxial and biaxial stresses. The results are compared with device bending data and piezoresistance data for uniaxial stress, and device data from strained Si channel on relaxed SiGe substrate devices for biaxial tensile stress. All comparisons show a very good agreement with simulation. It is found that the hole band structure is dominated by 12 ‘wings,’ where mechanical stress, as well as the vertical field under certain stress conditions, can alter the energies of the few lowest hole subbands, changing the transport effective mass, density-of-states, and scattering rates, and thus affecting the mobility. [ABSTRACT FROM AUTHOR]