Electronic transport in narrow gap semiconductors is characterized by spontaneous vertical transitions between carriers in the valence and conduction bands, a phenomenon also known as Zener tunneling. However, this effect is not captured by existing models based on the Boltzmann transport equation. In this work, we propose a new fully first principles model for electronic transport using the Wigner distribution function and implement it to solve the equations of motion for electrons. The formalism generalizes the Boltzmann equation to materials with strong interband coupling and include transport contributions from off-diagonal components of the charge current operator. We illustrate the method with a study of Bi₂Se₃, showing that interband tunneling dominates the electron transport dynamics at experimentally relevant small doping concentrations, a behavior that is likely shared with other semiconductors, including topological insulators. Surprisingly, Zener tunneling occurs also between band subvalleys separated by energy much larger than the band gap.

窄间隙半导体中的电子传输的特征在于价带和导带中载流子之间的自发垂直跃迁，这种现象也称为齐纳隧穿。但是，基于玻耳兹曼输运方程的现有模型无法捕获这种影响。在这项工作中，我们使用维格纳分布函数为电子传输提出了一个全新的完全第一性原理模型，并将其实现以解决电子的运动方程。形式主义将玻尔兹曼方程推广到带间耦合强的材料，并包括电荷电流算子的非对角线分量的传输贡献。我们通过研究Bi ₂ Se _3来说明该方法结果表明，在实验相关的小掺杂浓度下，带间隧穿支配了电子传输动力学，这种行为很可能与包括拓扑绝缘体在内的其他半导体共有。出乎意料的是，在被能量远大于带隙的能量隔开的带子谷之间，也发生了齐纳隧穿。