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We present quantum transport simulation results for InAs and In0.7Ga0.3As double-gate MOSFETs by using an atomistic full-band basis to evaluate the tunneling currents in the OFF state. While InAs has the advantage of lower mass and higher injection velocity, it also has lower bandgap. For low gate bias, the overlap in energy of the valence band in the channel with the source/drain conduction bands results in band-to-band tunneling (BTBT) between source and drain, which clamps the OFF current. Such current can be reduced by increasing the bandgap of the material either by increasing confinement or by lowering the In content, for example, using In0.7Ga0.3As. Grading the doping of the source/drain region to create a wider barrier also reduces BTBT, but to a lesser extent. [ABSTRACT FROM PUBLISHER]

We present a core compact model for undoped, high mobility, and low density of states materials in a double gate device architecture. Analytical equations for calculating current and charge are presented in a drift-diffusion compact modeling framework. This model accurately handles both Fermi–Dirac statistics and bias-dependent diffusivity. The results from analytical equations are validated against exact numerical charge and current integrations and device simulation. [ABSTRACT FROM PUBLISHER]

It is well known that, in a halo-implanted metal–oxide–semiconductor field-effect transistor, the application of the drain voltage lowers the threshold voltage even in a long-channel device. This phenomenon is known as the long-channel drain-induced barrier lowering (LDIBL) or the drain-induced threshold-voltage shift (DITS). In this paper, we will investigate the physical origin of this effect and will show that the root cause has not been previously identified properly. We will identify the physical phenomenon behind the LDIBL/DITS and present an analytic model. The proposed approach is validated against both the device simulation and measurement. [ABSTRACT FROM AUTHOR]

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]