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Title: Monte Carlo modeling of transport in PbSe nanocrystal films

A Monte Carlo hopping model was developed to simulate electron and hole transport in nanocrystalline PbSe films. Transport is carried out as a series of thermally activated hopping events between neighboring sites on a cubic lattice. Each site, representing an individual nanocrystal, is assigned a size-dependent electronic structure, and the effects of particle size, charging, interparticle coupling, and energetic disorder on electron and hole mobilities were investigated. Results of simulated field-effect measurements confirm that electron mobilities and conductivities at constant carrier densities increase with particle diameter by an order of magnitude up to 5 nm and begin to decrease above 6 nm. We find that as particle size increases, fewer hops are required to traverse the same distance and that site energy disorder significantly inhibits transport in films composed of smaller nanoparticles. The dip in mobilities and conductivities at larger particle sizes can be explained by a decrease in tunneling amplitudes and by charging penalties that are incurred more frequently when carriers are confined to fewer, larger nanoparticles. Using a nearly identical set of parameter values as the electron simulations, hole mobility simulations confirm measurements that increase monotonically with particle size over two orders of magnitude.
Authors:
;  [1] ;  [2]
  1. University of California, Santa Cruz, California 95060 (United States)
  2. University of California, Davis, California 95616 (United States)
Publication Date:
OSTI Identifier:
22258745
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 114; Journal Issue: 19; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; AMPLITUDES; CARRIER DENSITY; CARRIERS; CUBIC LATTICES; ELECTRON MOBILITY; ELECTRONIC STRUCTURE; FILMS; HOLE MOBILITY; HOLMIUM PHOSPHIDES; LEAD SELENIDES; MONTE CARLO METHOD; NANOSTRUCTURES; PARTICLE SIZE; PARTICLES; SIMULATION; TUNNEL EFFECT