A Systematic Study of Compositionally Dependent Dielectric Tensors of SnSxSe1-x Alloys by Spectroscopic Ellipsometry
| Autor: | Young Dong Kim, Tung Hoang Nguyen, Long Van Le, Thi Minh Hai Nguyen, Kyu-Jin Kim, Bogyu Kim, Tae Jung Kim, Wonjun Lee, Sunglae Cho, Xuan Au Nguyen |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Materials science
Band gap General Chemical Engineering Physics::Optics 02 engineering and technology Dielectric 01 natural sciences Inorganic Chemistry Condensed Matter::Materials Science anisotropic dielectric tensor Ellipsometry Critical point (thermodynamics) Saddle point 0103 physical sciences General Materials Science Anisotropy Electronic band structure 010302 applied physics Crystallography Condensed matter physics 021001 nanoscience & nanotechnology Condensed Matter Physics Zigzag QD901-999 SnSSe alloy 0210 nano-technology ellipsometry |
| Zdroj: | Crystals Volume 11 Issue 5 Crystals, Vol 11, Iss 548, p 548 (2021) |
| ISSN: | 2073-4352 |
| DOI: | 10.3390/cryst11050548 |
| Popis: | We report the dielectric tensors on the cleavage plane of biaxial SnSxSe1-x alloys in the spectral energy region from 0.74 to 6.42 eV obtained by spectroscopic ellipsometry. Single-crystal SnSxSe1-x alloys were grown by the temperature-gradient method. Strongly anisotropic optical responses are observed along the different principal axes. An approximate solution yields the anisotropic dielectric functions along the zigzag (a-axis) and armchair (b-axis) directions. The critical point (CP) energies of SnSxSe1-x alloys are obtained by analyzing numerically calculated second derivatives, and their physical origins are identified by energy band structure. Blue shifts of the CPs are observed with increasing S composition. The fundamental bandgap for Se = 0.8 and 1 in the armchair axis arises from band-to-band transitions at the M0 minimum point instead of the M1 saddle point as in SnS. These optical data will be useful for designing optoelectronic devices based on SnSxSe1-x alloys. |
| Databáze: | OpenAIRE |
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