Devices on vW Heterostructures
Quantum Devices in MoS2/h-BN Heterostructures
van der Waals heterostructures hold the advantage of large-scale uniformity, flexibility, portability and high-temperature operation over conventional bulk semiconductor heterostructures. vW materials would be the ideal platform to realize electrostatically defined nanoscale devices and to pave the way for flexible quantum electronics.
Layer Engineering and Phase Engineering MoS2
Etching and patterning of vW materials
A generic layer engineering technology using microwave plasma for controlled etching of vW materials to obtain large area samples of desired thickness without compromising device performance. Ability to pattern samples to desired shapes yields a scalable technique compatible with standard micro-fabrication schemes.
2H-1T MoS2 hybrid junctions
The presence of different polymorphic phases (semiconducting 2H, metallic 1T) make MoS2 a desirable platform to fabricate and study monolithic semiconducting/metallic junctions. Conventional 1T conversion processes are not scalable and also yield unstable samples. Using microwave plasma, we engineer a stable 1T phase in a scalable manner, compatible with standard device fabrication schemes. The 1T regions on the 2H sample can be achieved on desired regions.
2D Superconductivity in vW Systems
Unlike its 3D counterpart, superconductivity in 2D is interlaced with omnipresent vortices and their dynamics packed with rich physics and wide applications. Berisenskii Kosterlitz Thouless phase transition, Bose metal phase, and Ising superconductivity are seen in these systems.
2D superconductivity in 1T-MoS2
2D superconductivity is limited to systems with sheet resistance less than the resistance quantum, RQ = h/4e2 ~6.45 kΩ . The metallic nature and high carrier concentration make 1T, the metallic phase of MoS2, a natural choice for the study of 2D superconductivity.
Electrostatic control of quantum phases
Ionic liquid gating enables one to change the carrier concentration in a system by many orders which is not possible in conventional dielectric gating techniques. Quantum phases such as 2D superconductivity can be realised and explored in vW systems using this technique. On systems that lack centre of symmetry, interesting features such as Ising superconductivity can be observed.
Nanomechanical Resonators on 2D Systems
vW materials with excellent crystallinity, mechanical and electrical properties form a platform for coupling the electrical and mechanical degrees of freedom for novel device applications. Investigation of these systems are fascinating from a fundamental physics perspective and also has various technological applications such as quantum displacement sensors.