Current Research Projects
2D layered materials has unique properties due to their simple geometry and tunable band gap as a function of number of layers. Most of the semiconductors layered materials shows indirect band gaps in bulk single crystal and it goes transition to direct band gap in single atomic layer form.
- High Quality Crystal Growth (CVT)
We are interested in synthesizing different layered materials using chemical vapor transport technique (CVT). CVT method with proper growth condition could provide high quality crystals with minimizing the defect and impurity density. We are trying to grow TMDCs, Magnetic Materials as well as other 2D crystals.
Recent News
Dr Pradhan is with Prof. Mauricio Terrones (Penn State University) and Prof. Yuri Gogotsi (Drexel University) at ACS 2024 Conference, New Orleans on March, 18th, 2024
Nihar, Rukshan and Sumit attended the Quantum Materials Symposium at Florida State University, Tallahassee from April 6th-8th, 2023.
06/18/2024: Tech Connect World Innovation Conference & Expo @ Washington DC (With Dr Anirudha Sumant, Prof. Abha Misra, Dr Sachin Junnakar and students from Georgia Tech)
Congratulations Rukshan ! for his Best Poster Prize on "Localized measurements of dielectric properties of 2D MoS2 / PMMA nanocomposites" from Quantum Science and Engineering Material Symposium @ Florida State University
Congratulations Brian! for being a finalist of xTech HBCU Student competition by US Army office. Also receiving $2500 prize.
2. High Quality Field-effect Transistors on few-Layered TMDs and their Application in Logic Circuits
Field-effect transistor fabricated using single to few-atomic layers of layered materials such as transition metal dichalcogenides (TMDs) shows promising ON/OFF current ratio and subthreshold voltage swing. We are currently working on fabricating high quality FETs devices with low contact resistance. (i) Engineering metal contacts with lower work function of metals to lower the Schottky barrier height and improve the carrier mobility, (ii) Fabricating heterostructure functional devices with distinct 2D materials and (iii) increasing the crystal quality using different synthesis route. We are also working on the application of these 2D-FETs for inverters, signal amplifiers, oscillators and other logic elements.
Bilayer MoTe2 Field-effect transistors (right side figure): Single layer MoTe2 has band gap 1.1 eV shows promising application in FETs [N. R. Pradhan, ACS Nano 8 (6), 5911-5920 (2014)].
FETs fabricated on single to few-atomic layers of these layered materials such as transition metal dichalcogenides (TMDs) shows promising ON/OFF current ratio >10^6 and subthreshold voltage swing <150mV. The charge carrier mobility of few layered TMDs at room temperature varied from 20 to 500 cm^2/Vs and ON/OFF current ration from 10⁵ - 10⁸. Our aim is to improve the FETs properties using different metal contacts with lower Schottky barriers.
3. Metal-Insulator Quantum Phase Transition in TMDs:
Single to few-layered ReS2 shows very interesting transition from insulating to metallic behavior at low temperature under applied electric field as shown in right figure [N. R. Pradhan, Nano Letter 15 (12), 8377-8384]. We are interested in studying electrical transport properties of single to few-layered of these semiconductors layered crystals at low temperature under applied electric and magnetic field.
4. Layered TMDs as thinnest, transparent and flexible Photovoltaic solar cells
TMDs have band gap ranges from 0.8 to 3 eV and shows strong light matter interaction properties due to Van Hov singularities in the density of states. We are interested to study optical properties by building p-n junction solar cell devices s shown in Figure. 7 Nano Letter 15 (11), 7532 (2015)
5. Few Layered TMDs: High Responsivity Vis-IR Photosensor and Novel optical switching effect
Semiconducting Layered materials such as WSe2, MoS2, MoSe2 etc shows extremely high light matter interaction properties and practically possible to make high responsivity and External Quantum efficiency phototransistors or photodiodes. They also show novel optical switching properties and we are currently exploring them.
6. Developing High Density Energy Storage Thin film on Polymer based Nanocomposites and understanding their Interface Properties:
Polymers with suitable nanofillers such as 0D-to-2D nanofillers are prepared in different geometry to enhance the interface polarization as well as breakdown voltage to enahnce the over all dielectric properties and energy density. Recenty we explored a method and design principle to incorporate 2D fillers inside the polymer matrix to enhance the energy storage to a new height (ACS Nano).
