Band-Structure Effects in Ultrascaled Silicon Nanowires

In this paper, we investigate band-structure effects on the transport properties of ultrascaled silicon nanowire FETs operating under quantum-ballistic conditions. More specifically, we expand the dispersion relationship epsiv(kappa) in a power series up to the third order in kappa2 and generate the corresponding higher order operator to be used within the single-electron Hamiltonian for the solution of the Schrodinger equation. We work out a hierarchy of nonparabolic models accounting for the following: 1) the shift of the subband edges and the change in the transport effective masses; 2) the higher order Hamiltonian operator; and 3) the splitting of the fourfold unprimed subbands in nanometer-size FETs. We then compute the device turn-on characteristics, the threshold shift versus diameter, and the subthreshold slope (SS) versus gate length. By compensating for the different threshold voltages, i.e., by reducing the turn- on characteristics to the same leakage current at zero gate bias, it turns out that the current discrepancies between the most general model and the bulk-parabolic model are contained within 20%. Finally, it turns out that the nonparabolic band structure gives an improved SS at the lowest gate lengths due to a reduced source-drain tunneling, reaching up to 30% enhancement.

[1]  M. Rudan,et al.  Effects of the Band-Structure Modification in Silicon Nanowires with Small Diameters , 2006, 2006 European Solid-State Device Research Conference.

[2]  Gerhard Klimeck,et al.  On the Validity of the Parabolic Effective-Mass Approximation for the Current-Voltage Calculation of , 2005 .

[3]  Jing Wang,et al.  A three-dimensional quantum simulation of silicon nanowire transistors with the effective-mass approximation , 2004, cond-mat/0403739.

[4]  Fabio Beltram,et al.  Empirical spds^* tight-binding calculation for cubic semiconductors : general method and material parameters , 1998 .

[5]  Craig S. Lent,et al.  The quantum transmitting boundary method , 1990 .

[6]  Gerhard Klimeck,et al.  Single and multiband modeling of quantum electron transport through layered semiconductor devices , 1997 .

[7]  Mincheol Shin,et al.  Effects of atomistic defects on coherent electron transmission in Si nanowires: Full band calculations , 2001 .

[8]  On the Electrostatics of Double-Gate and Cylindrical Nanowire MOSFETs , 2004, 2004 Abstracts 10th International Workshop on Computational Electronics.

[9]  G. Klimeck,et al.  Electronic properties of silicon nanowires , 2005, IEEE Transactions on Electron Devices.

[10]  P. Durand,et al.  A theoretical method to determine atomic pseudopotentials for electronic structure calculations of molecules and solids , 1975 .

[11]  Parr,et al.  Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. , 1988, Physical review. B, Condensed matter.

[12]  Y. J. Park,et al.  A three-dimensional simulation of quantum transport in silicon nanowire transistor in the presence of electron-phonon interactions , 2006 .

[13]  J. A. López-Villanueva,et al.  A solution of the effective-mass Schrödinger equation in general isotropic and nonparabolic bands for the study of two-dimensional carrier gases , 2005 .

[14]  A. Becke.  Density-functional thermochemistry. , 1996 .

[15]  W. Fichtner,et al.  Three-Dimensional Full-Band Simulations of Si Nanowire Transistors , 2006, 2006 International Electron Devices Meeting.

[16]  H.-S.P. Wong,et al.  Extreme scaling with ultra-thin Si channel MOSFETs , 2002, Digest. International Electron Devices Meeting,.

[17]  D. Munteanu,et al.  Influence of band-structure on electron ballistic transport in silicon nanowire MOSFET's: an atomistic study , 2005, Proceedings of 35th European Solid-State Device Research Conference, 2005. ESSDERC 2005..

[18]  Ohno,et al.  Intrinsic origin of visible light emission from silicon quantum wires: Electronic structure and geometrically restricted exciton. , 1992, Physical review letters.

[19]  S. Datta,et al.  Simulating quantum transport in nanoscale transistors: Real versus mode-space approaches , 2002 .

[20]  Chenming Hu,et al.  5nm-gate nanowire FinFET , 2004, Digest of Technical Papers. 2004 Symposium on VLSI Technology, 2004..

[21]  David K. Ferry,et al.  Phonon-assisted ballistic to diffusive crossover in silicon nanowire transistors , 2005 .

[22]  P. Durand,et al.  New atomic pseudopotentials for electronic structure calculations of molecules and solids , 1974 .

[23]  W. Fichtner,et al.  Atomistic simulation of nanowires in the sp3d5s* tight-binding formalism: From boundary conditions to strain calculations , 2006 .

[24]  N. Mori,et al.  Three-Dimensional Quantum Transport Simulation of Ultra-Small FinFETs , 2004, 2004 Abstracts 10th International Workshop on Computational Electronics.