Ultrasensitive photodetectors exploiting electrostatic trapping and percolation transport
- Authors
- Zhang, Yingjie; Hellebusch, Daniel J.; Bronstein, Noah D.; Ko, Changhyun; Ogletree, D. Frank; Salmeron, Miquel; Alivisatos, A. Paul
- Issue Date
- Jun-2016
- Publisher
- NATURE PUBLISHING GROUP
- Citation
- NATURE COMMUNICATIONS, v.7, pp 1 - 9
- Pages
- 9
- Journal Title
- NATURE COMMUNICATIONS
- Volume
- 7
- Start Page
- 1
- End Page
- 9
- URI
- https://scholarworks.sookmyung.ac.kr/handle/2020.sw.sookmyung/3353
- DOI
- 10.1038/ncomms11924
- ISSN
- 2041-1723
- 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 × 1017 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 1010 e− per photon, and allows for effective control of the device response speed by active carrier quenching.
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