Anders Blom will give a talk at IEEE Nano 2017 in Pittsburgh, Pennsylvania on July 25-28.
The oral presentation will be on Wednesday 26 at 17:15-17:30, in section "Modeling and Simulation of Nanostructures and Nanodevices II", Paper WeO2O4.4. You can see the full programme here, and read the abstract below.
"We will demonstrate how it is possible to compute properties of SiGe alloys using modern first-principles approaches which provide values for the band gaps, as well as effective masses for Si and Ge (also when strain is applied) which are in agreement with experiments. We have performed an extensive study to benchmark a broad variety of methods in search of such a computationally efficient, yet accurate solution, and the results are very encouraging, not just for Si and Ge, but also for III-V semiconductors. In particular, the relatively unknown DFT+1/2 approach seems to very well be able to reproduce both band gaps and lattice properties, without incurring any significant computational overhead compared to usual DFT. Moreover, the method works well for oxides such as HfO2 and SiO2, giving band gaps that almost exactly agree with experiments. This means, that this method would be able to treat the entire device in e.g. a gate all-around nanowire geometry, including the oxide cladding and metallic source/drain electrodes, in an atomistic device simulator based on DFT+NEGF. We will present these findings, and show results for Si(1–x)Ge(x) for the full range of x. We will show how the commonly used virtual crystal approximation (VCA) fails to reproduce the non-linear dependence of the band gap and other properties as a function of composition, and moreover that a careful choice of how the SiGe alloy is represented is crucial for obtaining correct results, by comparing cells constructed using the special quasi-structures (SQS) method with purely randomized supercells."