title: Strong enhancement of photoresponsivity with shrinking the electrodes spacing in few layer GaSe photodetectors.
abstract: A critical challenge for the integration of optoelectronics is that photodetectors have relatively poor sensitivities at the nanometer scale. Generally, a large electrodes spacing in photodetectors is required to absorb sufficient light to maintain high photoresponsivity and reduce the dark current. However, this will limit the optoelectronic integration density. Through spatially resolved photocurrent investigation, we find that the photocurrent in metal-semiconductor-metal (MSM) photodetectors based on layered GaSe is mainly generated from the region close to the metal-GaSe interface with higher electrical potential. The photoresponsivity monotonically increases with shrinking the spacing distance before the direct tunneling happens, which was significantly enhanced up to 5,000 AW(-1) for the bottom Ti/Au contacted device. It is more than 1,700-fold improvement over the previously reported results. The response time of the Ti/Au contacted devices is about 10-20 ms and reduced down to 270 μs for the devices with single layer graphene as metallic electrodes. A theoretical model has been developed to well explain the photoresponsivity for these two types of device configurations. Our findings realize reducing the size and improving the performance of 2D semiconductor based MSM photodetectors simultaneously, which could pave the way for future high density integration of optoelectronics with high performances.
authors: SKLSM, Institute of Semiconductors, Chinese Academy of Science, P. O. Box 912, Beijing 100083, P. R. China.
authors: Yufei
authors: Y
authors: Cao
authors: SKLSM, Institute of Semiconductors, Chinese Academy of Science, P. O. Box 912, Beijing 100083, P. R. China.
authors: Kaiming
authors: K
authors: Cai
authors: KLMM, Harbin Institute of Technology, No. 2 YiKuang Street, Harbin, 150080, P.R. China.
authors: Pingan
authors: P
authors: Hu
authors: Semiconductor Lighting Technology Research and Development Center, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, P. R. China.
authors: Lixia
authors: L
authors: Zhao
authors: SKLSM, Institute of Semiconductors, Chinese Academy of Science, P. O. Box 912, Beijing 100083, P. R. China.
authors: Tengfei
authors: T
authors: Yan
authors: SKLSM, Institute of Semiconductors, Chinese Academy of Science, P. O. Box 912, Beijing 100083, P. R. China.
authors: Wengang
authors: W
authors: Luo
authors: SKLSM, Institute of Semiconductors, Chinese Academy of Science, P. O. Box 912, Beijing 100083, P. R. China.
authors: Xinhui
authors: X
authors: Zhang
authors: SKLSM, Institute of Semiconductors, Chinese Academy of Science, P. O. Box 912, Beijing 100083, P. R. China.
authors: Xiaoguang
authors: X
authors: Wu
authors: SKLSM, Institute of Semiconductors, Chinese Academy of Science, P. O. Box 912, Beijing 100083, P. R. China.
authors: Kaiyou
authors: K
authors: Wang
authors: SKLSM, Institute of Semiconductors, Chinese Academy of Science, P. O. Box 912, Beijing 100083, P. R. China.
authors: Houzhi
authors: H
authors: Zheng
references: Science. 2011 Nov 4;334(6056):648-52
references: 21979935
references: ACS Nano. 2014 Jan 28;8(1):752-60
references: 24364508
references: Science. 2004 Oct 22;306(5696):666-9
references: 15499015
references: Nat Nanotechnol. 2013 Jul;8(7):497-501
references: 23748194
references: Nat Nanotechnol. 2009 Dec;4(12):839-43
references: 19893532
references: Nat Commun. 2013;4:1643
references: 23535664
references: Nat Nanotechnol. 2012 Dec;7(12):798-802
references: 23142945
references: Nanoscale. 2014 Mar 7;6(5):2582-7
references: 24463644
references: Nat Nanotechnol. 2008 Aug;3(8):486-90
references: 18685636
references: ACS Nano. 2012 Jan 24;6(1):74-80
references: 22165908
references: ACS Nano. 2013 May 28;7(5):3905-11
references: 23590667
references: Phys Rev Lett. 2012 Jun 29;108(26):266805
references: 23005005
references: Sci Rep. 2014;4:3826
references: 24451916
references: Nat Commun. 2012;3:906
references: 22713748
references: Nano Lett. 2011 Oct 12;11(10):4134-7
references: 21879753
references: Nano Lett. 2012 Jun 13;12(6):2773-7
references: 22563791
references: Science. 2001 Aug 24;293(5534):1455-7
references: 11520977
references: ACS Nano. 2012 Jul 24;6(7):5988-94
references: 22676041
references: Nano Lett. 2013 Jun 12;13(6):2777-81
references: 23731066
references: Nat Nanotechnol. 2012 Jun;7(6):363-8
references: 22562036
references: Adv Mater. 2011 Dec 1;23(45):5419-24
references: 21786342
references: Adv Mater. 2012 Mar 15;24(11):1410-7
references: 22302415
references: Nat Nanotechnol. 2014 Apr;9(4):273-8
references: 24633521
references: Sci Rep. 2014 Feb 10;4:4041
references: 24509565