Research Projects

There is intense research being carried out towards realizing quantum and integrated nanophotonic platforms to cater to increasing demand on data capacity and speeds. An important aspect in this regard is the requirement for compact, efficient sources of light. Layered two-dimensional (2D) materials such as transition metal dichalcogenides (TMDs) have attracted tremendous interest in this regard as they possess several unique properties that are absent in the bulk form such as layer-dependent electronic band structure, strong excitonic effects, spin-valley physics, and nonlinear optical phenomena. A limitation with atomically thin layers of TMDs is that it limits the strength of light-matter interaction resulting in subpar performance of optoelectronic and photonic devices. While optical engineering of TMD emission has been shown in optical pumping configuration using photonic cavities and nanostructures, there have been very few attempts at realizing electrically pumped TMDs integrated with nanophotonic structures possibly due to a lack of uniform large area films. The latter is extremely significant in the context of practical applications, as such devices have lesser footprint and offers ease of tunability. This project aims to fill this gap to realize electroluminescence (EL) engineering in metasurface-integrated TMDs by approaching this problem from both material system and nanophotonic standpoints with implications from both applied and fundamental perspectives. Specific objectives include: (i) enhanced EL including spatially separated valley-polarized emissions as well as excitation/suppression of TMD excitons; (ii) strong exciton-polariton coupling in electrically pumped configuration; (iii) on-demand reconfigurability of these effects via the use of a phase change metasurface; (iv) direct nanostructuring of TMDs; and (v) development of engineered TMDs and heterostructures. Approaches to meet these objectives include simulations to identify suitable nanostructure designs, optimization of TMD growth, nanostructuring of high-index materials to create dielectric metasurfaces, and optoelectronic measurements of EL in a custom optical microscopy setup. Realization of nanostructure-integrated TMDs can enable seamless integration of efficient TMD-based light sources into CMOS-compatible architectures for use in integrated silicon photonic platforms. In addition, realization of electrically pumped strongly coupled TMDs can have tremendous implications for applications such as optical computers and inversionless lasers as it will enable scaling up of polaritonic devices. Finally, our approach to reconfigure TMD EL on-demand by the use of a phase change chalcogenide material platform could lead to efficient, dynamically tunable nanophotonic sources. The fundamental insights gaining from these objectives will be helping towards the advancements of TMDs in applications such as light sources, photodetectors, solar cells, and opto-valleytronic devices.