title: Exciton pumping across type-I gallium chalcogenide heterojunctions.
abstract: Quasi-two-dimensional gallium chalcogenide heterostructures are created by transferring exfoliated few-layer GaSe onto bulk GaTe sheets. Luminescence spectroscopy measurements reveal that the light emission from underlying GaTe layers drastically increases on heterojunction regions where GaSe layers make contact with the GaTe. Density functional theory (DFT) and band offset calculations show that conduction band minimum (CBM) (valance band maximum (VBM)) values of GaSe are higher (lower) in energy compared to GaTe, forming type-I band alignment at the interface. Consequently, GaSe layers provide photo-excited electrons and holes to GaTe sheets through relatively large built-in potential at the interface, increasing overall exciton population and light emission from GaTe. Observed results are not specific to the GaSe/GaTe system but observed on GaS/GaSe heterolayers with type-I band alignment. Observed experimental findings and theoretical studies provide unique insights into interface effects across dissimilar gallium chalcogenides and offer new ways to boost optical performance by simple epitaxial coating.
authors.affiliation: Materials Science and Engineering, School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Cai
authors.forename: Jun
authors.initials: J
authors.lastname: Kang
authors.forename: Hasan
authors.initials: H
authors.lastname: Sahin
authors.forename: Bin
authors.initials: B
authors.lastname: Chen
authors.forename: Aslihan
authors.initials: A
authors.lastname: Suslu
authors.forename: Kedi
authors.initials: K
authors.lastname: Wu
authors.forename: Francois
authors.initials: F
authors.lastname: Peeters
authors.forename: Xiuqing
authors.initials: X
authors.lastname: Meng
authors.forename: Sefaattin
authors.initials: S
authors.lastname: Tongay