Abstract:
The use of new materials opens up new ages for human beings. For example, silicon-based semiconductor technology creates a revolution of our daily life into the era of electronics. Thus, the exploration of new materials is crucial for developing next-generation electronics. Pioneered by graphene, new 2D materials exhibit abundant unusual physical phenomena that were undiscovered in bulk forms due to its unique electronic structure. The confinement of charge and heat transport at such ultrathin planes offers possibilities to overcome the bottleneck of present devices in thickness limitation and push the technologies into the next generation. While most researchers are struggling for large-scale manufacturing of these intriguing materials and device fabrication, less attention is paid to revisit existing 2D layered systems. Muscovite mica, a 2D layered oxide, is the largest available natural and synthetic 2D layered single crystal. In 2016, Chu’s group was the pioneer proposing to use muscovite mica as substrates to build up flexible electronics using inorganic materials[1], forming a research playground named “MICAtronics”. Due to its 2D feature, an atomically smooth surface can be obtained for van der Waals heteroepitaxy and superior mechanical flexibility can be utilized for bending conditions. Owing to its naturally thermal and chemical stabilities, the heterostructures made on mica show excellent environmental stability, standing out as an alternative solution to soft technology[2]. Various heteroepitaxies, including metal/muscovite, oxide/muscovite, and conventional semiconductor/muscovite were shown with lots of device demonstrations, delivering new material solutions for flexible devices and presenting a promising future for muscovite based flexible electronics. Currently, Chu’s group is the most active research group along this research direction. However, in these studies, muscovite simply serves as a flexible substrate, no critical functionality of muscovite is revealed. Thus, the key question we would like to address in this talk is: can we create new properties of muscovite by structural modification? Taking the nature of 2D layered structure of muscovite, a van der Waals gap of 0.3 nm exists in muscovite between layers, which can be viewed as a 2D cavity. The idea of this study is to use this 2D cavity to create new material form by insertion of chemical species, especially focusing on transition metal ions. Then, a heat treatment is implemented to transfer transition metal ions into crystalline form. During this process, the atmosphere will be controlled, expecting to deliver materials in metal, oxide, nitride, and carbide forms. The existence of these new formed systems with muscovite can be viewed as an atomic composite due the atomic layer stacking of the heterostructure. By a proper design, this atomic composite can show properties different from bare muscovite, delivering new substrate selection for flexible electronics.
Keywords – Composite, Muscovite, Flexible, Two-dimensional, Crystal
References:
- H. Chu, npj Quant. Mater. 2, 67 (2017).
- Bitla and Y. H. Chu, FlatChem 3, 26 (2017).