title: Photogeneration and Mobility of Charge Carriers in Atomically Thin Colloidal InSe Nanosheets Probed by Ultrafast Terahertz Spectroscopy.
abstract: The implementation of next generation ultrathin electronics by applying highly promising dimensionality-dependent physical properties of two-dimensional (2D) semiconductors is ever increasing. In this context, the van der Waals layered semiconductor InSe has proven its potential as photodetecting material with high charge carrier mobility. We have determined the photogeneration charge carrier quantum yield and mobility in atomically thin colloidal InSe nanosheets (inorganic layer thickness 0.8-1.7 nm, mono/double-layers, ≤ 5 nm including ligands) by ultrafast transient terahertz (THz) spectroscopy. A near unity quantum yield of free charge carriers is determined for low photoexcitation density. The charge carrier quantum yield decreases at higher excitation density due to recombination of electrons and holes, leading to the formation of neutral excitons. In the THz frequency domain, we probe a charge mobility as high as 20 ± 2 cm2/(V s). The THz mobility is similar to field-effect transistor mobilities extracted from unmodified exfoliated thin InSe devices. The current work provides the first results on charge carrier dynamics in ultrathin colloidal InSe nanosheets.
authors.affiliation: Chemical Engineering Department, Delft University of Technology , Van der Maasweg 9, NL-2629 HZ Delft, The Netherlands.
authors.forename: Jannika
authors.initials: J
authors.lastname: Lauth
authors.affiliation: Chemical Engineering Department, Delft University of Technology , Van der Maasweg 9, NL-2629 HZ Delft, The Netherlands.
authors.forename: Aditya
authors.initials: A
authors.lastname: Kulkarni
authors.affiliation: Chemical Engineering Department, Delft University of Technology , Van der Maasweg 9, NL-2629 HZ Delft, The Netherlands.
authors.forename: Frank C M
authors.initials: FCM
authors.lastname: Spoor
authors.affiliation: Chemical Engineering Department, Delft University of Technology , Van der Maasweg 9, NL-2629 HZ Delft, The Netherlands.
authors.forename: Nicolas
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authors.lastname: Renaud
authors.affiliation: Chemical Engineering Department, Delft University of Technology , Van der Maasweg 9, NL-2629 HZ Delft, The Netherlands.
authors.forename: Ferdinand C
authors.initials: FC
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authors.affiliation: Chemical Engineering Department, Delft University of Technology , Van der Maasweg 9, NL-2629 HZ Delft, The Netherlands.
authors.forename: Arjan J
authors.initials: AJ
authors.lastname: Houtepen
authors.affiliation: Chemical Engineering Department, Delft University of Technology , Van der Maasweg 9, NL-2629 HZ Delft, The Netherlands.
authors.forename: Juleon M
authors.initials: JM
authors.lastname: Schins
authors.affiliation: Toyota Motor Europe, Materials Research & Development , Hoge Wei 33, B-1930 Zaventem, Belgium.
authors.forename: Sachin
authors.initials: S
authors.lastname: Kinge
authors.affiliation: Chemical Engineering Department, Delft University of Technology , Van der Maasweg 9, NL-2629 HZ Delft, The Netherlands.
authors.forename: Laurens D A
authors.initials: LDA
authors.lastname: Siebbeles