Efficient and realistic device modeling from atomic detail to the nanoscale

As semiconductor devices scale to new dimensions, the materials and designs become more dependent on atomic details. NEMO5 is a nanoelectronics modeling package designed for comprehending the critical multi-scale, multi-physics phenomena through efficient computational approaches and quantitatively modeling new generations of nanoelectronic devices as well as predicting novel device architectures and phenomena. This article seeks to provide updates on the current status of the tool and new functionality, including advances in quantum transport simulations and with materials such as metals, topological insulators, and piezoelectrics.Comment: 10 pages, 12 figure

Elasticity theory of pseudomorphic heterostructures grown on substrates of arbitrary thickness

A theoretical model for lattice mismatched pseudomorphically grown heterostructure, which is based on continuum elasticity theory is described. Two distinct types of coherently grown structures are considered, namely, those grown on a thick substrate and these grown on a freestanding one. Special cases of structures that are homogeneous or periodic in some directions are considered. The theory can be applied for an arbitrary crystallographic direction of the heterostructure growth. The model has been applied to AlN/GaN nanocolumn and GaAs/InAs heterostructure. Calculation of strain induced shape deformation is shown

Full-band tunneling in high-kappa oxide MOS structures

In this paper, we investigate the tunneling properties of ZrO2 and HfO2 high-kappa oxides, by applying quantum mechanical methods that include the full-band structure of Si and oxide materials. Semiempirical sp(3)s*d tight-binding parameters have been determined to reproduce ab-initio band dispersions. Transmission coefficients and tunneling currents have been calculated for Si/ZrO2/Si and Si/HfO2/Si MOS structures, showing a very low gate leakage current in comparison to SiO2-based structures with the same equivalent oxide thickness. The complex band structures of ZrO2 and HfO2 have been calculated and used to develop an energy-dependent effective tunneling mass model. We show that effective mass calculations based on this model yield tunneling currents in close agreement with full-band results

Simulation of exciton formation and transport in electrically driven polariton laser structures

A model for exciton formation, dissociation and transport is proposed for the simulation of an electrically pumped polariton laser with a geometry similar to that of a VCSEL and resonant cavity LEDs. We demonstrate how the strain effects and the geometry of the device influence the exciton distribution for a GaN/InGaN laser structure

Tunneling properties of MOS systems based on high-k oxides

In this work, we show full-band calculations of the tunneling properties of ZrO2 and HfO2 high-kappa oxides. First, we have determined serniernpirical sp(3)s*d tight-binding (TB) parameters which reproduce ab-initio band dispersions of the high-kappa oxides; then we have calculated transmission coefficients and tunneling currents for Si/ZrO2/Si and Si/HfO2/Si MOS structures. Results show a very low gate leakage current in comparison to SiO2-based structures with the same equivalent oxide thickness. The complex band structures of ZrO2 and HfO2 have been calculated; based on them we develop an energy dependent effective tunneling mass model. It is shown that this model can be used to obtain effective mass tunneling currents close to full band results