First-principles calculations of Stark shifts of electronic transitions for defects in semiconductors: the Si vacancy in 4H-SiC
First-principles calculations of Stark shifts of electronic transitions for defects in semiconductors: the Si vacancy in 4H-SiC
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DOI：
10.1088/1361-648x/abc804
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发表时间：
2020-02-17
影响因子：
2.7
通讯作者：
Coutinho, Jose
中科院分区：
文献类型：
--
作者：
Bathen, Marianne Etzelmuller;Vines, Lasse;Coutinho, Jose
固体中的点缺陷是一种很有前途的单光子源，在量子传感、计算和通信等领域有着广泛的应用。在此，我们描述了一个基于周期边界条件下密度泛函理论计算的理论框架，用于研究电场对缺陷相关电子跃迁的影响。锯齿形电场垂直于二维缺陷板的表面，在真空层中放置感应电荷奇点。采用4H-SiC中的硅空位（V-Si）作为基准体系，在近红外中具有三个零声子线（V1, V1 '和V2），并通过制造肖特基势垒或p-i-n二极管表现出斯塔克可调性。与实验观察一致，我们发现V-Si的零声子跃迁具有近似线性的场响应，涉及从第一激发态（称为V1和V2）衰减。然而，与实验结果相比，斯塔克变化的幅度被高估了近10倍。我们讨论了可能影响协议的几个理论和实验方面。
Point defects in solids are promising single-photon sources with application in quantum sensing, computing and communication. Herein, we describe a theoretical framework for studying electric field effects on defect-related electronic transitions, based on density functional theory calculations with periodic boundary conditions. Sawtooth-shaped electric fields are applied perpendicular to the surface of a two-dimensional defective slab, with induced charge singularities being placed in the vacuum layer. The silicon vacancy (V-Si) in 4H-SiC is employed as a benchmark system, having three zero-phonon lines in the near-infrared (V1, V1 ' and V2) and exhibiting Stark tunability via fabrication of Schottky barrier or p-i-n diodes. In agreement with experimental observations, we find an approximately linear field response for the zero-phonon transitions of V-Si involving the decay from the first excited state (named V1 and V2). However, the magnitude of the Stark shifts are overestimated by nearly a factor of 10 when comparing to experimental findings. We discuss several theoretical and experimental aspects which could affect the agreement.