title: Evolution of the electronic band structure and efficient photo-detection in atomic layers of InSe.
abstract: Atomic layers of two-dimensional (2D) materials have recently been the focus of extensive research. This follows from the footsteps of graphene, which has shown great potential for ultrathin optoelectronic devices. In this paper, we present a comprehensive study on the synthesis, characterization, and thin film photodetector application of atomic layers of InSe. Correlation between resonance Raman spectroscopy and photoconductivity measurements allows us to systematically track the evolution of the electronic band structure of 2D InSe as its thickness approaches few atomic layers. Analysis of photoconductivity spectra suggests that few-layered InSe has an indirect band gap of 1.4 eV, which is 200 meV higher than bulk InSe due to the suppressed interlayer electron orbital coupling. Temperature-dependent photocurrent measurements reveal that the suppressed interlayer interaction also results in more localized pz-like orbitals, and these orbitals couple strongly with the in-plane E' and E″ phonons. Finally, we measured a strong photoresponse of 34.7 mA/W and fast response time of 488 μs for a few layered InSe, suggesting that it is a good material for thin film optoelectronic applications.
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University , Houston, Texas 77005, United States.
authors.forename: Sidong
authors.initials: S
authors.lastname: Lei
authors.forename: Liehui
authors.initials: L
authors.lastname: Ge
authors.forename: Sina
authors.initials: S
authors.lastname: Najmaei
authors.forename: Antony
authors.initials: A
authors.lastname: George
authors.forename: Rajesh
authors.initials: R
authors.lastname: Kappera
authors.forename: Jun
authors.initials: J
authors.lastname: Lou
authors.forename: Manish
authors.initials: M
authors.lastname: Chhowalla
authors.forename: Hisato
authors.initials: H
authors.lastname: Yamaguchi
authors.forename: Gautam
authors.initials: G
authors.lastname: Gupta
authors.forename: Robert
authors.initials: R
authors.lastname: Vajtai
authors.forename: Aditya D
authors.initials: AD
authors.lastname: Mohite
authors.forename: Pulickel M
authors.initials: PM
authors.lastname: Ajayan