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

doi:10.1038/ncomms11924

Ultrasensitive photodetectors exploiting electrostatic trapping and percolation transport

Nat Commun. 2016 Jun 21:7:11924. doi: 10.1038/ncomms11924.

Authors

Yingjie Zhang^{1

2}, Daniel J Hellebusch^{2

3

4}, Noah D Bronstein^{2

4

5}, Changhyun Ko⁶, D Frank Ogletree⁷, Miquel Salmeron^{2

6}, A Paul Alivisatos^{2

4

5

6}

Affiliations

¹ Applied Science and Technology Graduate Program, University of California, Berkeley, California 94720, USA.
² Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.
³ Department of Chemical Engineering, University of California, Berkeley, California 94720, USA.
⁴ Kavli Energy NanoScience Institute, Berkeley, California 94720, USA.
⁵ Department of Chemistry, University of California, Berkeley, California 94720, USA.
⁶ Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA.
⁷ The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.

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.

Publication types

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