skip to main content

SciTech ConnectSciTech Connect

Title: Gated Si nanowires for large thermoelectric power factors

We investigate the effect of electrostatic gating on the thermoelectric power factor of p-type Si nanowires (NWs) of up to 20 nm in diameter in the [100], [110], and [111] crystallographic transport orientations. We use atomistic tight-binding simulations for the calculation of the NW electronic structure, coupled to linearized Boltzmann transport equation for the calculation of the thermoelectric coefficients. We show that gated NW structures can provide ∼5× larger thermoelectric power factor compared to doped channels, attributed to their high hole phonon-limited mobility, as well as gating induced bandstructure modifications which further improve mobility. Despite the fact that gating shifts the charge carriers near the NW surface, surface roughness scattering is not strong enough to degrade the transport properties of the accumulated hole layer. The highest power factor is achieved for the [111] NW, followed by the [110], and finally by the [100] NW. As the NW diameter increases, the advantage of the gated channel is reduced. We show, however, that even at 20 nm diameters (the largest ones that we were able to simulate), a ∼3× higher power factor for gated channels is observed. Our simulations suggest that the advantage of gating could still be present in NWs with diameters ofmore » up to ∼40 nm.« less
Authors:
 [1] ;  [2]
  1. School of Engineering, University of Warwick, Coventry CV4 7AL (United Kingdom)
  2. Institute for Microelectronics, Vienna University of Technology, Gusshausstrasse 27-29/E360, Vienna A-1040 (Austria)
Publication Date:
OSTI Identifier:
22311345
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 7; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; BOLTZMANN EQUATION; CARRIER MOBILITY; CHARGE CARRIERS; DOPED MATERIALS; ELECTRONIC STRUCTURE; HOLES; LAYERS; MODIFICATIONS; NANOWIRES; POWER FACTOR; QUANTUM WIRES; ROUGHNESS; SIMULATION; SURFACES; THERMOELECTRICITY