Photoluminescence dynamics in few-layer InSe

Venanzi, Tommaso; Arora, Himani; Winnerl, Stephan; Pashkin, Alexej; Chava, Phanish; Patane, Amalia; Kovalyuk, Zakhar D.; Kudrynskyi, Zakhar R.; Watanabe, Kenji; Taniguchi, Takashi; Erbe, Artur; Helm, Manfred; Schneider, Harald

Abstract

We study the optical properties of thin flakes of InSe encapsulated in hBN. More specifically, we investigate the photoluminescence (PL) emission and its dependence on sample thickness and temperature. Through the analysis of the PL lineshape, we discuss the relative weights of the exciton and electron-hole contributions. Thereafter we investigate the PL dynamics. Two contributions are distinguishable at low temperature: direct bandgap electron-hole and defect-assisted recombination. The two recombination processes have lifetime of τ1 ∼ 8 ns and τ2 ∼ 100 ns, respectively. The relative weights of the direct bandgap and defect-assisted contributions show a strong layer dependence due to the direct-to-indirect bandgap crossover. Electron-hole PL lifetime is limited by population transfer to lower-energy states and no dependence on the number of layers was observed. The lifetime of the defect-assisted recombination gets longer for thinner samples. Finally, we show that the PL lifetime decreases at high temperatures as a consequence of more efficient non-radiative recombinations.

Citation

Venanzi, T., Arora, H., Winnerl, S., Pashkin, A., Chava, P., Patane, A., Kovalyuk, Z. D., Kudrynskyi, Z. R., Watanabe, K., Taniguchi, T., Erbe, A., Helm, M., & Schneider, H. (2020). Photoluminescence dynamics in few-layer InSe. Physical Review Materials, 4(4), Article 044001. https://doi.org/10.1103/PhysRevMaterials.4.044001

• Journal Article Type: Article
• Acceptance Date: Mar 25, 2020
• Online Publication Date: Apr 14, 2020
• Publication Date: Apr 1, 2020
• Deposit Date: Mar 27, 2020
• Publicly Available Date: Apr 1, 2020
• Journal: Physical Review Materials
• Electronic ISSN: 2475-9953
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 4
• Issue: 4
• Article Number: 044001
• DOI: https://doi.org/10.1103/PhysRevMaterials.4.044001
• Public URL: https://nottingham-repository.worktribe.com/output/4210827
• Publisher URL: https://journals.aps.org/prmaterials/abstract/10.1103/PhysRevMaterials.4.044001
• Additional Information: Photoluminescence dynamics in few-layer InSe, Tommaso Venanzi, Himani Arora, Stephan Winnerl, Alexej Pashkin, Phanish Chava, Amalia Patanè, Zakhar D. Kovalyuk, Zakhar R. Kudrynskyi, Kenji Watanabe, Takashi Taniguchi, Artur Erbe, Manfred Helm, and Harald Schneider; Phys. Rev. Materials 4, 044001