Photocurrent polarization anisotropy of randomly oriented nanowire networks

Nano Lett. 2008 May;8(5):1352-7. doi: 10.1021/nl080028p. Epub 2008 Apr 5.

Abstract

While the polarization sensitivity of single or aligned NW ensembles is well-known, this article reports on the existence of residual photocurrent polarization sensitivities in random NW networks. In these studies, CdSe and CdTe NWs were deposited onto glass substrates and contacted with Au electrodes separated by 30-110 microm gaps. SEM and AFM images of resulting devices show isotropically distributed NWs between the electrodes. Complementary high resolution TEM micrographs reveal component NWs to be highly crystalline with diameters between 10 and 20 nm and with lengths ranging from 1 to 10 microm. When illuminated with visible (linearly polarized) light, such random NW networks exhibit significant photocurrent anisotropies rho = 0.25 (sigma = 0.04) [rho = 0.22 (sigma = 0.04)] for CdSe (CdTe) NWs. Corresponding bandwidth measurements yield device polarization sensitivities up to 100 Hz. Additional studies have investigated the effects of varying the electrode potential, gap width, and spatial excitation profile. These experiments suggest electrode orientation as the determining factor behind the polarization sensitivity of NW devices. A simple geometric model has been developed to qualitatively explain the phenomenon. The main conclusion from these studies, however, is that polarization sensitive devices can be made from random NW networks without the need to align component wires.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Anisotropy
  • Cadmium Compounds / chemistry*
  • Cadmium Compounds / radiation effects
  • Crystallization / methods*
  • Electrochemistry / methods*
  • Electromagnetic Fields
  • Light
  • Materials Testing
  • Molecular Conformation
  • Nanostructures / chemistry*
  • Nanostructures / radiation effects
  • Nanostructures / ultrastructure
  • Nanotechnology / methods
  • Particle Size
  • Photochemistry / methods*
  • Refractometry / methods*
  • Selenium Compounds / chemistry*
  • Selenium Compounds / radiation effects
  • Tellurium / chemistry*
  • Tellurium / radiation effects
  • Transducers

Substances

  • Cadmium Compounds
  • Selenium Compounds
  • cadmium selenide
  • Tellurium
  • cadmium telluride