First-principles modeling of electron transport.

Area of Science:

• Computational physics and materials science
• Quantum mechanics and condensed matter physics

Background:

• Electronic device dimensions are rapidly decreasing, necessitating advanced modeling tools.
• Atomic-scale details and quantum effects are crucial for accurately predicting device electrical properties.

Purpose of the Study:

• To present the framework and applications of density functional theory within the non-equilibrium Green's function formalism (NEGF-DFT).
• To demonstrate the applicability of NEGF-DFT for nanoscale electronic device modeling.
• To explore the scalability of NEGF-DFT for large systems relevant to semiconductor device modeling.

Main Methods:

• Utilizing density functional theory (DFT) combined with the non-equilibrium Green's function (NEGF) formalism.
• Calculating I-V characteristics of molecular junctions.
• Simulating spin-dependent electron transport in magnetic tunnel junctions.

Main Results:

• Accurate calculation of I-V characteristics for a single molecule connected to gold electrodes.
• Successful simulation of spin-dependent electron transport through a Fe/MgO/Fe magnetic tunnel junction.
• Demonstration of linear scaling for important classes of systems, enabling modeling of thousands of atoms.

Conclusions:

• NEGF-DFT is a powerful framework for modeling nanoscale electronic devices.
• The method accurately captures quantum effects and atomic-scale details.
• Linear scaling advancements make NEGF-DFT suitable for large-scale semiconductor device modeling.