title: Synthesis and photoresponse of large GaSe atomic layers.
abstract: We report the direct growth of large, atomically thin GaSe single crystals on insulating substrates by vapor phase mass transport. A correlation is identified between the number of layers and a Raman shift and intensity change. We found obvious contrast of the resistance of the material in the dark and when illuminated with visible light. In the photoconductivity measurement we observed a low dark current. The on-off ratio measured with a 405 nm at 0.5 mW/mm(2) light source is in the order of 10(3); the photoresponsivity is 17 mA/W, and the quantum efficiency is 5.2%, suggesting possibility for photodetector and sensor applications. The photocurrent spectrum of few-layer GaSe shows an intense blue shift of the excitation edge and expanded band gap compared with bulk material.
authors.affiliation: Department of Mechanical Engineering and Materials Science, Rice University, Houston, Texas 77005, USA.
authors.forename: Sidong
authors.initials: S
authors.lastname: Lei
authors.forename: Liehui
authors.initials: L
authors.lastname: Ge
authors.forename: Zheng
authors.initials: Z
authors.lastname: Liu
authors.forename: Sina
authors.initials: S
authors.lastname: Najmaei
authors.forename: Gang
authors.initials: G
authors.lastname: Shi
authors.forename: Ge
authors.initials: G
authors.lastname: You
authors.forename: Jun
authors.initials: J
authors.lastname: Lou
authors.forename: Robert
authors.initials: R
authors.lastname: Vajtai
authors.forename: Pulickel M
authors.initials: PM
authors.lastname: Ajayan