Ab initio electron dynamics in high electric fields: accurate predictions of velocity-field curves

TL;DR

This paper introduces an efficient first-principles method to accurately simulate electron dynamics in high electric fields, enabling detailed insights into charge transport and scattering mechanisms in materials like silicon, GaAs, and graphene.

Contribution

The authors develop a real-time Boltzmann transport equation solver incorporating ab initio electron-phonon interactions for high-field electron dynamics prediction.

Findings

Quantitative agreement with experimental velocity-field curves.

Detailed analysis of scattering mechanisms and valley occupation.

Accurate modeling of transient and steady-state electron transport.

Abstract

Electron dynamics in external electric fields governs the behavior of solid-state electronic devices. First-principles calculations enable precise predictions of charge transport in low electric fields. However, studies of high-field electron dynamics remain elusive due to a lack of accurate and broadly applicable methods. Here we develop an efficient approach to solve the real-time Boltzmann transport equation with both the electric field term and ab initio electron-phonon collisions. These simulations provide field-dependent electronic distributions in the time domain, allowing us to investigate both transient and steady-state transport in electric fields ranging from low to high (>10 kV/cm). The broad capabilities of our approach are shown by computing nonequilibrium electron occupations and velocity-field curves in Si, GaAs, and graphene, obtaining results in quantitative agreement with experiment. Our approach sheds light on microscopic details of transport in high electric fields, including dominant scattering mechanisms and valley occupation dynamics. Our results demonstrate quantitatively accurate calculations of electron dynamics in low-to-high electric fields, with broad application to power- and micro-electronics, optoelectronics, and sensing.