Localized Strain Measurement in Molecular Beam Epitaxially Grown Chalcogenide Thin Films by Micro-Raman Spectroscopy
[1];
[2];
[3]
- Tianjin Key Laboratory of High Speed Cutting and Precision Machining, Tianjin University of Technology and Education, Tianjin 300222, China, Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716, United States
- Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, United States
- Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716, United States
- Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716, United States, State Key Laboratory for Mesoscopic Physics & Department of Physics Collaborative Innovation Center of Quantum Matter, Peking University, Beijing 100871, China
We developed an experimental metrology for measuring local strain in molecular beam epitaxially (MBE) grown crystalline chalcogenide thin films through micro-Raman spectroscopy. For In2Se3 and Bi2Se3 on c-plane sapphire substrates, the transverse-optical vibrational mode (A1 phonon) is most sensitive to strain. We first calibrated the phonon frequency–strain relationship in each material by introducing strain in flexible substrates. The Raman shift–strain coefficient is -1.97 cm–1/% for the In2Se3 A1(LO + TO) mode and -1.68 cm–1/% for the Bi2Se3 A1g2 mode. In2Se3 and Bi2Se3 samples exhibit compressive strain and tensile strain, respectively. The observations are compliant with predictions from the opposite relative thermal expansion coefficient between the sample and the substrate. We also map strain cartography near the edge of as-grown MBE samples. In In2Se3, the strain accumulates with increasing film thickness, while a low strain is observed in thicker Bi2Se3 films.
- Research Organization:
- Tianjin Univ. of Technology and Education (China); Univ. of Delaware, Newark, DE (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); National Natural Science Foundation; US Air Force Office of Scientific Research (AFOSR); National Aeronautics and Space Administration (NASA); National Science Foundation (NSF)
- Grant/Contract Number:
- SC0016380; 11772227; 11772223; AFOSR YIP FA9550-18-1-0300; NASA ECF 80NSSC17K0526; DMR-1652994
- OSTI ID:
- 1607809
- Alternate ID(s):
- OSTI ID: 1616406; OSTI ID: 1886897
- Journal Information:
- ACS Omega, Journal Name: ACS Omega; ISSN 2470-1343
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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