Being a good thermoelectric material is a balancing act between high electrical conductivity σ and low thermal conductivity κ, because both quantities depend directly on the flow of electrons. Fortunately, κ also depends on lattice phonons, so this contribution can be cut—for example, by scattering from randomly distributed heavy atoms. The authors’ calculations show that adding tin to alloys of silicon and germanium should yield quite good thermoelectrics, especially in thin-film systems.
This article studies how thermal conductivity in graphene ribbons scales with their length and uncovers an unusual logarithmic dependence, while also explaining the eventual convergence beyond 100 um–far longer than the phonon mean free path!
The Lilly Fellowship is a competitive award program, established in 1986, that enables promising junior faculty to cultivate teaching excellence in a special yearlong collaboration. More information about Prof. Aksamija and other awardees here:
The Rising Researcher award is presented to Gabriela Calinao Correa, class of two-thousand-sixteen, for her dedicated pursuit of research with meaningful, tangible, and publishable results. Gabriela’s Honors Thesis led to the development of a new computational model for heat transfer between 2D van der Waals materials (such as graphene) blanketing 3D substrates used in the semiconductor industry to build nanoelectronic devices. She gave a talk on this research at the fall 2015 Materials Research Society Meeting in Boston, Massachusetts, a rare opportunity for an undergraduate researcher. Gabriela’s faculty advisor is Zlatan Aksamija, electrical and computer engineering. Congratulations, Gabriela!
More information about the award at ResearchNext: http://www.umass.edu/researchnext/researcher/passionate-pursuit
The Nanoelectronics Theory and Simulation Lab is fortunate to have been selected as a recipient of 2 NVIDIA Tesla K40 GPU cards (adding up to a total of 5760 cores, capable of 8.6 Tflops performance!) to accelerate our calculations. This award is part of NVIDIA’s Academic Hardware Grant Program.
This invention, co-invented with Prof. Robert Blick of the University of Hamburg, uses folded 2-dimensional materials to reach enhanced thermoelectric conversion efficiencies. 2-D materials like grapheme are great electrical and thermal conductors; by folding them, the thermal path is suppressed, diverting more thermal energy into electrical, thereby increasing thermoelectric conversion efficiency:
Our team is part of a multi-university collaboration with UIC and MIT which has been awarded the recent $2 million NSF Emerging Frontiers in Research and Innovation (EFRI) 2-DARE grant to study thermal properties of 2-dimensional van der Waals heterostructures. Read more about it from the UMass press release:
Or check out the NSF summary/abstract of the award here:
Here is a link to the UMass ECE article about the recent media coverage of my research on grain boundaries in graphene, performed together with graduate student Arnab Majee and our collaborators at the University of Illinois at Chicago: