On the validity of the parabolic effective-mass approximation for the I-V calculation of silicon nanowire transistors

This paper examines the validity of the widely used parabolic effective-mass approximation for computing the current-voltage (I-V) characteristics of silicon nanowire transistors (SNWTs). The energy dispersion relations for unrelaxed Si nanowires are first computed by using an sp/sup 3/d/sup 5/s/sup */ tight-binding (TB) model. A seminumerical ballistic field-effect transistor model is then adopted to evaluate the I-V characteristics of the (n-type) SNWTs based on both a TB dispersion relation and parabolic energy bands. In comparison with the TB approach, the parabolic effective-mass model with bulk effective-masses significantly overestimates SNWT threshold voltages when the wire width is <3 nm, and ON-currents when the wire width is <5 nm. By introducing two analytical equations with two tuning parameters, however, the effective-mass approximation can well reproduce the TB I-V results even at a /spl sim/1.36-nm wire width.

[1]  Gerhard Klimeck,et al.  Performance evaluation of ballistic silicon nanowire transistors with atomic-basis dispersion relations , 2005 .

[2]  Mark S. Lundstrom,et al.  Theory of ballistic nanotransistors , 2003 .

[3]  Gerhard Klimeck,et al.  Valence band effective-mass expressions in the sp 3 d 5 s * empirical tight-binding model applied to a Si and Ge parametrization , 2004 .

[4]  M. Lundstrom.  Fundamentals of carrier transport , 1990 .

[5]  Mark Lundstrom,et al.  Ballistic transport in high electron mobility transistors , 2003 .

[6]  Boundary conditions for the electronic structure of finite-extent embedded semiconductor nanostructures , 2003, cond-mat/0311461.

[7]  Charles M. Lieber,et al.  High Performance Silicon Nanowire Field Effect Transistors , 2003 .

[8]  E. Polizzi,et al.  A computational study of ballistic silicon nanowire transistors , 2003, IEEE International Electron Devices Meeting 2003.

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

[10]  Yuan Taur,et al.  Fundamentals of Modern VLSI Devices , 1998 .

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

[12]  A. Rahman,et al.  Bandstructure effects in ballistic nanoscale MOSFETs , 2004, IEDM Technical Digest. IEEE International Electron Devices Meeting, 2004..

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

[14]  Weichung Wang,et al.  Numerical methods for semiconductor heterostructures with band nonparabolicity , 2003 .

[15]  T. Hiramoto,et al.  Impact of quantum mechanical effects on design of nano-scale narrow channel n- and p-type MOSFETs , 2001, International Electron Devices Meeting. Technical Digest (Cat. No.01CH37224).

[16]  T. Boykin,et al.  Atomistic Approach for Nanoscale Devices at the Scaling Limit and Beyond– Valley Splitting in Si , 2005 .

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

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

[19]  S. Tomić,et al.  Influence of conduction-band nonparabolicity on electron confinement and effective mass in GaNxAs1−x∕GaAs quantum wells , 2004 .

[20]  L. Reggiani,et al.  Hot-Electron Transport in Semiconductors , 1985 .

[21]  Gerhard Klimeck,et al.  Valley splitting in low-density quantum-confined heterostructures studied using tight-binding models , 2004 .

[22]  J. Kavalieros,et al.  High performance fully-depleted tri-gate CMOS transistors , 2003, IEEE Electron Device Letters.

[23]  M. Chou,et al.  Quantum confinement and electronic properties of silicon nanowires. , 2004, Physical review letters.

[24]  Gerhard Klimeck,et al.  Valley splitting in strained silicon quantum wells , 2003 .