Stanene is one of most important of 2D materials due to its potential to demonstrate room temperature topological effects due to opening of spin-orbit gap. In this pursuit we report synthesis and investigation of optical properties of stanene up to few layers, a two-dimensional hexagonal structural analogue of graphene. Atomic scale morphological and elemental characterization using HRTEM equipped with SAED and EDAX detectors confirm the presence of hexagonal lattice of Sn atoms. The position of Raman peak along with the inter-planar ‘d’ spacing obtained from SAED for prepared samples are in good agreement with that obtained from first principles calculations and confirm that the sheets are not (111) α-Sn sheets. Further, the optical signature calculated using density functional theory at ~191 nm and ~233 nm for low buckled stanene are in qualitative agreement with the measured UV-Vis absorption spectrum. AFM measurements suggest interlayer spacing of ~0.33 nm in good agreement with that reported for epitaxial stanene sheets. No traces of oxygen were observed in the EDAX spectrum suggesting the absence of any oxidized phases. This is also confirmed by Raman measurements by comparing with oxidized stanene sheets.

Two-photon lithography (TPL) is a versatile technology for additive manufacturing of 2D and 3D micro/nanostructures with sub-wavelength resolved features. Recent advancement in laser technology has enabled the application of TPL fabricated structures in several fields such as microelectronics, photonics, optoelectronics, microfluidics, and plasmonic devices. However, the lack of two-photon polymerizable resins (TPPRs) induces bottleneck to the growth of TPL to its true potential, and hence continuous research efforts are focused on developing efficient TPPRs. In this article, we review the recent advancements in PI and TPPR formulation and the impact of process parameters on fabrication of 2D and 3D structures for specific applications. The fundamentals of TPL are described, followed by techniques used for achieving improved resolution and functional micro/nanostructures. Finally, a critical outlook and future prospects of TPPR formulation for specific applications are presented.

The extraordinary success of graphene in various applications has led to the quest to innovate techniques for production and patterning of nanomaterials. Numerous techniques such as vapor deposition, epitaxial growth, mechanical and chemical exfoliation have been explored to achieve this goal. These new methods have enabled the synthesis of a monolayer to a few layer graphene structures, in various forms such as films, nanoribbons, and 3D nanocomposites that are dispersed in solutions, suspended or deposited on substrates. However, several challenges still exist in processing graphene for futuristic device fabrication. Thus, there is a need to review the traditional processing and synthesis techniques developed for obtaining graphene. This review will provide a solid foundation on technology development for achieving economical and high throughput synthesis of high quality graphene for scalable applications. In this review, we provide a brief discussion on the theory of graphene, discuss synthesis techniques along with conventional and recent approaches to pattern graphene structures, and conclude with an emphasis on direct patterning methods. Discussions on the properties of graphene produced using different techniques and their emerging applications will assist in selecting an appropriate methodology for achieving desired properties in graphene. This is expected to be instrumental in the development of new strategies for fabrication of futuristic graphene-based devices.