Photogeneration and Mobility of Charge Carriers in Atomically Thin Colloidal InSe Nanosheets Probed by Ultrafast Terahertz Spectroscopy

Jannika Lauth, Aditya Kulkarni, Frank C M Spoor, Nicolas Renaud, Ferdinand C. Grozema, Arjan J. Houtepen, Juleon M. Schins, Sachin Kinge, Laurens D A Siebbeles

Research output: Contribution to journalArticleScientificpeer-review

27 Citations (Scopus)
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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.

Original languageEnglish
Pages (from-to)4191-4196
Number of pages6
JournalThe Journal of Physical Chemistry Letters
Volume7
Issue number20
DOIs
Publication statusPublished - 20 Oct 2016

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