电子与自旋声合控制了拓绝缘体中的温度依赖载体动力学
Haoran Lu1, Run Long1, Wei-Hai Fang1
1College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, People's Republic of China.
Journal of the American Chemical Society
|November 15, 2023
概括
在拓绝缘体 (TI) 中,电子-声子合会影响电荷放松. 旋声合会影响表面动力学,导致在不同温度下长寿命的电荷载体.
科学领域:
- 凝聚物质物理学
- 材料科学
背景情况:
- 在拓绝缘体 (TI) 应用中,超快充和旋转动力学至关重要.
- 了解TI中的放松机制对于设备开发至关重要.
研究的目的:
- 在3D TI Bi2Te3中研究温度依赖的电荷和旋转放松动态.
- 通过体积和表面状态区分放松路径.
主要方法:
- 旋转 - 协同的非协同的分子动力学模拟.
- 包括电子 - 声子 (e-ph) 和自旋 - 声子合.
- 分析带内和带间的动态.
主要成果:
- 电子-声子合主导着散装电荷放松,随着温度的增加而增加.
- 旋声合驱动表面放松与相反的温度依赖.
- 在散装 (低T) 和表面 (室T) 状态下,电荷载体具有较长的寿命.
- 热波动会破坏旋转动量的锁定,并在室温下诱导反散.
结论:
- 在Bi2Te3的体积和表面状态下,有不同的机制控制电荷和旋转放松.
- 温度在确定电荷载体寿命和TI中的散射方面起着至关重要的作用.
- 旋声合和热效应是限制TI在较高温度下的关键因素.
相关概念视频
Carrier Generation and Recombination
586
Carrier generation is the process by which electron-hole pairs (EHPs) are created within the semiconductor. In direct-bandgap semiconductors, such as gallium arsenide (GaAs), this occurs efficiently when energy absorption prompts valence electrons to leap into the conduction band, leaving behind holes.
This process is given by the generation rate G and is efficient due to the conservation of momentum between the valence band maximum and conduction band minimum.
Indirect generation involves an...
This process is given by the generation rate G and is efficient due to the conservation of momentum between the valence band maximum and conduction band minimum.
Indirect generation involves an...
586
Carrier Transport
450
The generation of electrical current in semiconductors is fundamentally driven by two mechanisms: drift and diffusion. These processes are essential for the functionality and performance of semiconductor-based devices.
Drift Current:
The drift of charge carriers is started by an external electric field (E). Charged particles, such as electrons and holes, experience an acceleration between collisions with lattice atoms. For electrons, this results in a drift velocity (vd) given by:
Drift Current:
The drift of charge carriers is started by an external electric field (E). Charged particles, such as electrons and holes, experience an acceleration between collisions with lattice atoms. For electrons, this results in a drift velocity (vd) given by:
450
Types of Semiconductors
618
Intrinsic semiconductors are highly pure materials with no impurities. At absolute zero, these semiconductors behave as perfect insulators because all the valence electrons are bound, and the conduction band is empty, disallowing electrical conduction. The Fermi level is a concept used to describe the probability of occupancy of energy levels by electrons at thermal equilibrium. In intrinsic semiconductors, the Fermi level is positioned at the midpoint of the energy gap at absolute zero. When...
618
Theory of Metallic Conduction
1.3K
The conduction of free electrons inside a conductor is best described by quantum mechanics. However, a classical model makes predictions close to the results of quantum mechanics. It is called the theory of metallic conduction.
In this theory, Newton's second law of motion is used to determine the acceleration of an electron in the presence of an applied electric field. Then, its velocity is expressed via this acceleration.
An electron moves through the crystal, containing positive ions,...
In this theory, Newton's second law of motion is used to determine the acceleration of an electron in the presence of an applied electric field. Then, its velocity is expressed via this acceleration.
An electron moves through the crystal, containing positive ions,...
1.3K
Fermi Level
627
The Fermi-Dirac function is represented by an S-shaped curve indicating the probability of an energy state being occupied by an electron at a given temperature. The Fermi level is the energy level at which there is a fifty percent chance of finding an electron, and it is positioned between the lower-energy valence band and the higher-energy conduction band.
At absolute zero temperature, electrons fill all energy states up to the Fermi level, leaving upper states empty. As the temperature rises,...
At absolute zero temperature, electrons fill all energy states up to the Fermi level, leaving upper states empty. As the temperature rises,...
627
Atomic Nuclei: Nuclear Spin State Population Distribution
988
Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy spin-down state. As temperatures increase, the energy from thermal collisions distributes the spins more equally between the two states. The Boltzmann distribution equation gives the ratio of the number of spins predicted in the spin −½ (N−) and spin +½ (N+) states.
988


