title: Asymmetric Light Excitation for Photodetectors Based on Nanoscale Semiconductors.
abstract: A photodetector is a key device to extend the cognition fields of mankind and to enrich information transfer. With the advent of emerging nanomaterials and nanophotonic techniques, new explorations and designs for photodetection have been constantly put forward. Here, we report the asymmetric-light-excitation photoelectric detectors with symmetric electrical contacts working at zero external bias. Unlike conventional photodetectors with symmetric contacts which are usually used as photoconductors or phototransistors showing no photocurrent at zero bias, in this device, the asymmetric-light-excitation structure is designed to ensure that only one Schottky junction between two metallic electrodes and semiconductors is illuminated. In this condition, a device can contribute to a photocurrent without bias. Furthermore, incident light with global illumination will be redistributed by the top Au patterns on devices. The achievement of detectors benefits from the designed redistribution of optical field on specific Schottky barriers within optically active regions and effective carrier collection, producing unidirectional photocurrent for large-scale detection applications. The response mechanisms, including excitations under different polarizations, wavebands, and tilted incidences, were systematically elaborated. Device performances including photocurrent, dynamic response, and detectivity were also carefully measured, demonstrating the possibility for applications in high-speed imaging sensors or integrated optoelectronic systems. The concept of asymmetric-light-excitation photodetectors shows wider availability to other nanomaterials for modern optoelectronics.
authors.forename: Shuang
authors.initials: S
authors.lastname: Liang
authors.forename: Feifan
authors.initials: F
authors.lastname: Wang
authors.forename: Ze
authors.initials: Z
authors.lastname: Ma
authors.forename: Nan
authors.initials: N
authors.lastname: Wei
authors.forename: Gongtao
authors.initials: G
authors.lastname: Wu
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences , Beijing 100190, China.|Collaborative Innovation Center of Quantum Matter , Beijing 100190, China.
authors.forename: Huaping
authors.initials: H
authors.lastname: Liu
authors.affiliation: Collaborative Innovation Center of Quantum Matter , Beijing 100190, China.
authors.forename: Xiaoyong
authors.initials: X
authors.lastname: Hu
authors.forename: Sheng
authors.identifier: 0000-0003-2605-2768
authors.initials: S
authors.lastname: Wang
authors.forename: Lian-Mao
authors.initials: LM
authors.lastname: Peng
keywords: Schottky barrier; asymmetric excitation; carbon nanotube; photocurrent; photodetector