Study of Oxidation and Polarization-Dependent Optical Properties of Environmentally Stable Layered GaTe Using a Novel Passivation Approach
| Autor: | David Tuschel, Thomas Murray, Spyros Gallis, Mounika Kotha |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Photoluminescence
Materials science Passivation General Chemical Engineering Nanophotonics chemistry.chemical_element 02 engineering and technology anisotropy 010402 general chemistry 01 natural sciences Article lcsh:Chemistry symbols.namesake raman spectroscopy General Materials Science Gallium business.industry 2d materials hydrogen silsesquioxane 021001 nanoscience & nanotechnology gallium telluride 0104 chemical sciences Semiconductor chemistry lcsh:QD1-999 pseudo-one-dimensional materials symbols Optoelectronics photoluminescence Photonics 0210 nano-technology Tellurium Raman spectroscopy business |
| Zdroj: | Nanomaterials, Vol 9, Iss 11, p 1510 (2019) Nanomaterials Volume 9 Issue 11 |
| ISSN: | 2079-4991 |
| Popis: | Emerging two-dimensional gallium chalcogenides, such as gallium telluride (GaTe), are considered promising layered semiconductors that can serve as vital building blocks towards the implementation of nanodevices in the fields of nanoelectronics, optoelectronics, and quantum photonics. However, oxidation-induced electronic, structural, and optical changes observed in ambient-exposed gallium chalcogenides need to be further investigated and addressed. Herein, we report on the thickness-dependent effect of air exposure on the Raman and photoluminescence (PL) properties of GaTe flakes, with thicknesses spanning in the range of a few layers to 100 nm. We have developed a novel chemical passivation that results in complete encapsulation of the as-exfoliated GaTe flakes in ultrathin hydrogen&ndash silsesquioxane (HSQ) film. A combination of correlation and comparison of Raman and PL studies reveal that the HSQ-capped GaTe flakes are effectively protected from oxidation in air ambient over the studied-period of one year, and thus, preserving their structural and optical characteristics. This contrasts with the behavior of uncapped GaTe, where we observe a significant reduction of the GaTe-related PL (~100× ) and Raman (~4× ) peak intensities for the few-layered flakes over a period of few days. The time-evolution of the Raman spectra in uncapped GaTe is accompanied by the appearance of two new prominent broad peaks at ~130 cm&minus 1 and ~146 cm&minus 1, which are attributed to the formation of polycrystalline tellurium, due to oxidation of ambient-exposed GaTe. Furthermore, and by leveraging this novel passivation, we were able to explore the optical anisotropy of HSQ-capped GaTe flakes. This is caused by the one-dimensional-like nature of the GaTe layer, as the layer comprises Ga&ndash Ga chains extending along the b-axis direction. In concurrence with high-resolution transmission electron microscopy analysis, polarization-dependent PL spectroscopy was used to identify the b-axis crystal direction in HSQ-capped GaTe flakes with various thicknesses over a range of wavelengths (458 nm&ndash 633 nm). Thus, our novel surface-passivation offers a new approach to explore and reveal the physical properties of the layered GaTe, with the potential of fabricating reliable polarization-dependent nanophotonics with structural and optical stability. |
| Databáze: | OpenAIRE |
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