Ultrasensitive photodetectors exploiting electrostatic trapping and percolation transport

Yingjie Zhang, Daniel J. Hellebusch, Noah D. Bronstein, Changhyun Ko, D. Frank Ogletree, Miquel Salmeron, A. Paul Alivisatos

Research output: Contribution to journalArticlepeer-review

Abstract

The sensitivity of semiconductor photodetectors is limited by photocarrier recombination during the carrier transport process. We developed a new photoactive material that reduces recombination by physically separating hole and electron charge carriers. This material has a specific detectivity (the ability to detect small signals) of 5 × 10 17 Jones, the highest reported in visible and infrared detectors at room temperature, and 4-5 orders of magnitude higher than that of commercial single-crystal silicon detectors. The material was fabricated by sintering chloride-capped CdTe nanocrystals into polycrystalline films, where Cl selectively segregates into grain boundaries acting as n-type dopants. Photogenerated electrons concentrate in and percolate along the grain boundaries - a network of energy valleys, while holes are confined in the grain interiors. This electrostatic field-assisted carrier separation and percolation mechanism enables an unprecedented photoconductive gain of 10 10 e - per photon, and allows for effective control of the device response speed by active carrier quenching.

Original languageEnglish (US)
Article number11924
JournalNature communications
Volume7
DOIs
StatePublished - Jun 21 2016
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

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