Quantitative characterization of carrier transport in nanowire photodetectors

Y. Gu, J. P. Romankiewicz, Lincoln James Lauhon*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


Scanning photocurrent microscopy was used to study carrier transport processes in semiconductor nanowire photodetectors. Under high-level local carrier injection in CdS nanowire devices, spatially non-uniform photocurrent distributions were observed and explained in terms of bipolar transport with spatially separated electrons and holes. The mobility-lifetime product, (μτ)*, for both electrons and holes was determined in intrinsic CdS nanowire photodetectors under high-level injection. (μτ)* was enhanced compared to the bulk values as a result of the carrier spatial separation. Local time-resolved photocurrent measurements supported this interpretation of the enhanced (μτ)*. Global time-resolved photocurrent measurements were used to establish a 10%-90% rise time of ∼ 6ns (limited by the instrument response) and a 90%-10% fall time of ∼ 20ns for the nanowire photodetectors. A small fraction of the total photocurrent exhibited a long power-law decay attributed to carrier trapping/detrapping processes, and characteristic shallow trap energy of 60meV was extracted. Spatially uniform photocurrent profiles were observed in Si nanowire photodetectors under low-level injection conditions, consistent with unipolar minority carrier transport. Under varying biases, consistent variations in the photocurrent profiles were observed and attributed to the effect of the applied electric fields on drift and diffusion of minority carriers.

Original languageEnglish (US)
Title of host publicationQuantum Sensing and Nanophotonic Devices IV
StatePublished - May 24 2007
EventQuantum Sensing and Nanophotonic Devices IV - San Jose, CA, United States
Duration: Jan 22 2007Jan 25 2007


OtherQuantum Sensing and Nanophotonic Devices IV
Country/TerritoryUnited States
CitySan Jose, CA


  • Carrier transport
  • Nanowire photodetectors
  • Photocurrent

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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