At the nanometer scale the concepts of device and material meet and a new device is a new material and vice versa. While atomistic device representations are novel to device physicists, the semiconductor materials modeling community usually treats infinitely periodic structures. NEMO 3-D bridges the gap and enables 52 million atom electronic structure simulations of quantum dots, quantum wells, nanowires, and impurities with relevant device dimensions. The new OMEN code enables quantum transport in atomistically resolved systems.
Two electronic structure calculation examples will illustrate the importance of atomistic disorder in realistically large systems. For strained Si quantum wells on wafer-miscut SiGe substrates valley splitting is computed as a function of magnetic field. For InAs quantum dots embedded in an InGaAs strain reducing layer on top of a GaAs substrate NEMO 3-D can model the non-linear optical transition energy dependence as a function of In-concentration. Both simulation sets match experimental data without adjustment to the NEMO 3-D material parameters or device geometries.
Electron and hole transport simulations through atomistically represented systems remain computationally and even conceptually challenging. Quantum transport simulations of high mobility transistors and band-to-band-tunneling transistors will be shown using the next generation OMEN tool. Both NEMO 3-D and OMEN perform very well on parallel machines and demonstrated efficient usage of up to 8,192 and 222,720 processors, respectively.
Ultimately these simulation tools will have the most impact if they can leave the hands of computational scientists and be put into the hands of experimentalists and educators. nanoHUB.org provides a platform for such tool deployment and we will highlight our achievements and plans on tool deployment of OMEN and NEMO3D on the nanoHUB.
203 Physics, Purdue University, West Lafayette, IN