Ph.D. student 2018-current,
Blue Waters Undergrad intern 2014-2015
Research: first principles methods for the calculation of phonon properties, including dispersion and phonon-phonon coupling. Their application to thermal properties of nanomembranes and 2D materials under strain and across material heterointerfaces.
Discoveries: thermal conductivity in Si and Ge nanomembranes is anisotropic and thickness dependent. Cross-plane thermal conductivity is highly sensitive to strain, with compressive (tensile) strain increasing (decreasing) the conductivity across the membrane, while leaving the in-plane direction unchanged, thus boosting anisotropy.
NanoEnergy Lab Alumni:
Ph.D. student Fall 2014-Spring 2021
Research: thermal transport in disordered semiconductor alloys, nanocomposites, and organic thermoelectrics.
Discoveries: phonon transport in Si-Ge alloy nanowires is superdiffusive, causing the thermal conductivity to increase with the cube root of the nanowire’s length. Dopant-induced disorder and clustering affect the Seebeck vs. conductivity trade-off in polymer thermoelectrics, limiting their TE conversion efficiency.
Ph.D. Student Fall 2016-Spring 2021
Research: electronic transport and thermoelectricity in semiconductor nanostructures using the Wigner formalism.
Discoveries: quantum effects in semiconductor nanostructures can enhance the Seebeck coefficient. Twisted bilayer graphene exhibits high thermoelectric power factors at angles near the so-called “magic” angle.
Undergraduate research, senior honors thesis (2019-2020) and (2020-2021)
XSEDE Empower intern: http://computationalscience.org/xsede-empower
Arnab K. Majee
M.S. 2014-2016, Ph.D. 2016-2020
now at U. New Mexico and Sandia National Lab
Research: thermal and electronic transport in 2D materials, including graphene and transition metal dichalcogenides (TMDCs) such as MoS2.
Discoveries: thermal conductivity in graphene nanoribbons diverges logarithmically with length up to 10 microns in length. Grain boundaries in MoS2 do not contribute significantly to electrical resistance, so polycrystalline MoS2 has nearly the same electrical conductivity as single-crystalline MoS2!
M.S. student 2018-2020, now at GlobalFoundries
Research: thermal transport simulation from first principles, Density Functional Theory calculations of phonons and anharmonic phonon-phonon interactions, phonon Boltzmann transport equation
M.S. student 2016-2020, now at Intel
Research: thermoelectric properties of group IV alloys containing Sn (Si-Sn, Ge-Sn).
Discoveries: thermoelectric properties of Si-Sn alloys are twice as good as those of Si-Ge owing to the large difference in mass between Si and Sn. This makes Si-Sn alloys an interesing potential candidate for high ZT thermoelectrics.
Akshaya Sandeep Waingade
M. S. student 2017-2019
Research: phonon boundary scattering, nanoscale heat transport, phonon Monte Carlo simulation
M.S. student 2014-2016
Research: thermal transport in Si-Sn and Ge-Sn alloys
Currently: Ph.D. candidate in Mechanical Engineering at UMass
Senior Thesis 2015-2016
Currently DOE/NSF fellow at Cornell University
Haoxian (Justin) Lin
summer REU student, May-Aug. 2017
Research: electronic and vibrational properties of 2-dimensional materials from first principles using Quantum Espresso calculations. Zone unfolding from supercells.