Defect induced Raman shifts and bandgap engineering in layered SnSe2+δ bulks

Author:

Lu Hong12ORCID,Zang Haotong1ORCID,Lai Zhigang3ORCID,An Wei4ORCID,Ni Vera15ORCID,Rodionova Valeria5ORCID,Magomedov Kurban5ORCID,Ren Xiao36ORCID

Affiliation:

1. College of Material Science and Engineering, Qiqihar University 1 , Qiqihar 161006, China

2. Heilongjiang Provincial Key Laboratory of Polymetric Composition Materials 2 , Qiqihar 161006, China

3. Key Laboratory of Materials Physics, Ministry of Education, School of Physics, Zhengzhou University 3 , Zhengzhou 450001, China

4. Sino-French Engineer School, Beihang University 4 , Beijing 100191, China

5. Research and Education Center for Smart Materials and Biomedical Applications, Immanuel Kant Baltic Federal University 5 , Kaliningrad 236041, Russia

6. Institute of Quantum Materials and Physics, Henan Academy of Sciences 6 , Zhengzhou 450046, China

Abstract

In the context of the extensive application prospect of two-dimensional (2D) chalcogenides, we synthesized layered SnSe2+δ bulks with defects employing a hybrid chemical vapor transport-melt approach. Both the Eg and A1g Raman characteristic peaks in SnSe2+δ are dominated by cubic anharmonicity, coupled with nonlinear temperature dependencies below 140 K. Notably, the reduction in phonon energy observed in these vibrational modes can be ascribed to defect-mediated Raman scattering, irrespective of deficient or excess Se defects. However, the lower consistency in the Raman shifts of the in-plane Eg vibrations compared to the out-of-plane A1g modes suggests that the defects predominantly entail the absence of Se atoms and the substitutions of Sn by Se, delineating a continuum of Se-deficient and Se-enriched compositions. Furthermore, Se defects induce the contraction of the indirect bandgaps, facilitating a transition from medium to narrow bandgap semiconductors in SnSe2+δ, which underscores the tunable nature of the bandgaps through the incorporation of Se defects. These discoveries present an avenue for bandgap engineering and foster a deeper comprehension of the phonon and thermal properties of layered chalcogenides for further advanced technologies.

Funder

Basic Scientific Research Functional Expense of Heilongjiang Provincial Colleges and Universities

National Natural Science Foundation of China

Natural Science Foundation of Heilongjiang Province

Key Research & Development and Promotion Project of Henan Province

College Student Innovation and Entrepreneurship Plan Project

Publisher

AIP Publishing

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