We are a research group in the Physics Department of Free University Berlin (Germany) specializing in nanoscale electronics and optoelectronics. Our main focus is two-dimensional atomic crystals – a recently discovered class of materials that are only atoms thick. These include: graphene, atomically thick form of carbon with record electrical conductivity, thermal conductivity, and strength; monolayer transition metal dichalcogenides (MoS2, WSe2, MoSe2), semiconductors strongly interacting with light, and monolayer boron nitride (BN), an atomically-smooth insulator material. Our overarching goal is to answer the following questions:
    • How does one controllably create, pattern, and manipulate two-dimensional atomic crystals? Is it possible to manipulate properties of these materials by cutting them or by stacking them into heterostructures?
    • What happens to interacting electrons that are confined in two dimensions and are governed by the laws of quantum mechanics? How do they interact with light? Is it possible to create electronic circuitry and optoelectronic devices that are based on graphene and other two-dimensional atomic crystals?
    • What are the mechanical properties of atomically-thick materials? Can we use nanoelectromechanical devices based on graphene to sense ultrasmall forces and weigh ultralight objects?

    We are equally interested in potential applications of our research. We would like to explore the potential of graphene and other two-dimensional materials towards applications in electronics; design nanoelectromechanical mass and force sensors capable of weighing individual atoms; create graphene biosensors for biomedical applications. A big part of our research is nanoscale fabrication. We use the facilities at Vanderbilt Institute of Nanoscale Science and Engineering and Oak Ridge National Laboratory to make, contact, cut, fold, and stack with atomic precision various two-dimensional materials from graphene to boron nitride.  

    Recent highlights of group’s work:

    Excitons in monolayer MoS2. We demonstrated electrical and mechanical modulation of bound electron/hole pairs, or excitons,  in monolayer MoS2. The work is published in Nano Letters and Solid State Comm.

    Probing liquids at the nanoscale with graphene FETs. We showed that transistors made of single sheets of graphene can be used to electrically interrogate nanoscale volumes of liquid. The work is published in Nature Communications and Nano LettersPress coverage: Vanderbilt News

    Quantum transport in ultrahigh mobility graphene. We fabricated suspended monolayer graphene specimens, demonstrated ultrahigh mobility in these devices, and observed the Fractional Quantum Hall Effect in graphene. The work in published in NaturePress coverage: Nature News and Views, PhysOrg, ScienceDaily

    Nanomechanics of graphene. We probed mechanical properties of single sheets of graphene and used graphene resonators to weigh tiny masses. The work is published in Nature Nanotechnology and Nano Letters.

    We gratefully acknowledge funding from:
    • European Council 
    • Freie Universitat Berlin
    • National Science Foundation
    • Office of Naval Research
    • Defense Threat Reduction Agency
    • Sloan Foundation
    • Vanderbilt University

    Open positions: Currently looking for motivated graduate and undergraduate students to work on electronic properties and device applications of graphene! Contact me via  email/chat or simply stop by my office if interested.

    The group: Internal group site (to track projects progress and to share relevant information). Ask me if you need to get access to it!