Ultrasensitive photodetectors exploiting electrostatic trapping and percolation transport

作者：Zhang Yingjie; Hellebusch Daniel J; Bronstein Noah D; Ko Changhyun; Ogletree D Frank; Salmeron Miquel^*; Alivisatos A Paul^*

来源：Nature Communications, 2016, 7(1): 11924.

DOI：10.1038/ncomms11924

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 x 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.

• 出版日期2016-6