Three distinct optical-switching states in phase-change materials containing impurities: From physical origin to material design
| Autor: | Zhongbo Yang, Shuaipeng Tao, Kaicheng Xu, Chaoquan Hu, Chaobin Bi, Ling Zhang, Weitao Zheng |
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| Rok vydání: | 2021 |
| Předmět: |
Phase transition
Materials science Polymers and Plastics Chalcogenide 02 engineering and technology 010402 general chemistry 01 natural sciences Optical switch symbols.namesake chemistry.chemical_compound Impurity Materials Chemistry Condensed matter physics business.industry Mechanical Engineering Metals and Alloys 021001 nanoscience & nanotechnology 0104 chemical sciences Amorphous solid Atomic radius chemistry Mechanics of Materials Ceramics and Composites symbols van der Waals force Photonics 0210 nano-technology business |
| Zdroj: | Journal of Materials Science & Technology. 75:118-125 |
| ISSN: | 1005-0302 |
| DOI: | 10.1016/j.jmst.2020.09.043 |
| Popis: | Ge2Sb2Te5 is the most widely utilized chalcogenide phase-change material for non-volatile photonic applications, which undergoes amorphous-cubic and cubic-hexagonal phase transition under external excitations. However, the cubic-hexagonal optical contrast is negligible, only the amorphous-cubic phase transition of Ge2Sb2Te5 is available. This limits the optical switching states of traditional active displays and absorbers to two. We find that increasing structural disorder difference of cubic-hexagonal can increase optical contrast close to the level of amorphous-cubic. Therefore, an amorphous-cubic-hexagonal phase transition with high optical contrast is realized. Using this phase transition, we have developed display and absorber with three distinct switching states, improving the switching performance by 50 %. Through the combination of first-principle calculations and experiments, we reveal that the key to increasing structural disorder difference of amorphous, cubic and hexagonal phases is to introduce small interstitial impurities (like N) in Ge2Sb2Te5, rather than large substitutional impurities (like Ag) previously thought. This is explained by the formation energy and lattice distortion. Based on the impurity atomic radius, interstitial site radius and formation energy, C and B are also potential suitable impurities. In addition, introducing interstitial impurities into phase-change materials with van der Waals gaps in stable phase such as GeSb4Te7, GeSb2Te4, Ge3Sb2Te6, Sb2Te3 will produce high optical contrast amorphous-metastable-stable phase transition. This research not only reveals the important role of interstitial impurities in increasing the optical contrast between metastable-stable phases, but also proposes varieties of candidate matrices and impurities. This provides new phase-change materials and design methods for non-volatile optical devices with multi-switching states. |
| Databáze: | OpenAIRE |
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