Shu-Jen Han, Ph.D. - US grants

Technical Description: This GOALI project aims to create a robust and reproducible bandgap in graphene. To achieve this goal, superlattices of various geometries are studied, tailoring the band structure, the effective mass, carrier group velocity and other electronic properties of the metamaterials. The project involves collaboration between academia (Purdue University) and industry (IBM T.J. Watson Research Center). One of the experimental approaches is to use a nano-patterning mask to create graphene superlattices with aggressively scaled lattice dimensions and true periodicities. Another approach involves utilizing an external potential with a superlattice periodicity imprinted onto graphene. A comparison of the electronic properties of periodically patterned graphene metamaterials and gated graphene enables an in-depth study of the impact of edge states on the band structures of the metamaterials. The success of this research project can provide a general solution to fabricating superlattices in two-dimensional materials by nano-scale patterning.

Non-technical Description: This research project addresses one of the most pressing challenges in the graphene field: how to create a robust and reproducible bandgap to enable practical uses of graphene in analog and digital electronics. Through a joint study between Purdue University and IBM, novel patterning methods are investigated in order to achieve the periodic and reproducible features required for bandgap creation. In addition, this project provides opportunities for the training of graduate and undergraduate students in materials science, nano-patterning, and device engineering. The PI is also committed to participate in and contribute to educational outreach programs at Purdue University.

Establishing the foundation for electronics technology based on atomically thin two-dimensional (2D) materials, such as layered transition metal dichalcogenides (TMDCs), may prove to be transformative in many technological areas relying on flexible electronic and nanoelectronic systems. This project will establish a critical knowledge base for future 2D TMDC electronics technology for a broad range of applications, such as low power computing, flexible display, and wearable electronics. The project has a direct industrial impact through the respective collaboration and technology transfer between the participating universities and the industrial partner. It will also offer interdisciplinary research opportunities for training graduate students, as well as undergraduate and high school students, in a collaborative research environment between university and industry, and provide valuable resources for research and educational community by disseminating web-based learning modules, simulators, and experimental data on TDMC-based electronics.

While TMDC materials are promising for many potential applications in nanoelectronics and flexible electronics due to their mechanical bendability, atomically thin thickness, and excellent intrinsic carrier transport properties, major gaps exist on translating early science of such materials into practical circuit and system technologies. The objective of this project is to develop compact model and circuit-simulation platform for new 2D TMDC-based devices and systems, and to explore its applications in flexible and wearable electronic systems through experimental demonstration and collaboration with IBM T. J. Watson Research Center as the industrial partner. The proposal will undertake the following tasks: (i) develop a multiscale simulation framework that integrates atomistic device simulations with compact circuit models for TMDC transistors, (ii) fabricate, characterize and simulate basic TMDC circuits, (iii) model the variability and defect mechanisms and their correlations in TMDC transistors, and (iv) design and experimentally demonstrate TMDC driving circuits for transparent flexible display.