Ultrasensitive photodetectors exploiting electrostatic trapping and percolation transport.
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.
Applied Science and Technology Graduate Program, University of California, Berkeley, California 94720, USA.|Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.
Yingjie
Y
Zhang
Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.|Department of Chemical Engineering, University of California, Berkeley, California 94720, USA.|Kavli Energy NanoScience Institute, Berkeley, California 94720, USA.
Daniel J
DJ
Hellebusch
Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.|Kavli Energy NanoScience Institute, Berkeley, California 94720, USA.|Department of Chemistry, University of California, Berkeley, California 94720, USA.
Noah D
ND
Bronstein
Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA.
Changhyun
C
Ko
The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
D Frank
DF
Ogletree
Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.|Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA.
Miquel
M
Salmeron
Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.|Kavli Energy NanoScience Institute, Berkeley, California 94720, USA.|Department of Chemistry, University of California, Berkeley, California 94720, USA.|Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA.
A Paul
AP
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