Orbital Stark effect and quantum confinement transition of donors in silicon
Orbital Stark effect and quantum confinement transition of donors in silicon
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硅中施主的轨道斯塔克效应和量子限制跃迁
DOI：
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发表时间：
2009
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影响因子：
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通讯作者：
L. Hollenberg
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作者：
R. Rahman;G. Lansbergen;Seung;J. Verduijn;Gerhard Klimeck;S. Rogge;L. Hollenberg
近些年来，半导体中单杂质束缚电子绝热穿梭到栅致表面态的研究引起了人们的极大关注，主要是在固态量子计算机体系结构的背景下。最近的一项传输光谱实验首次能够探测埋藏在靠近栅极的硅中的单个施主的斯塔克位移光谱。在这里，我们提出了完整的理论模型，包括大规模的量子力学模拟，该模型被用来计算斯塔克移位的施主状态，以解释实验数据。在100多万个原子的区域上使用原子紧束缚技术不仅有助于整合主体的完整能带结构，还有助于处理现实的器件几何形状和施主模型，并使用足够大的基组来捕获任意数量的施主状态。该方法定量描述了当电场绝热上升时施主电子从三维库仑受限态到二维表面态的对称性转变。在中场区域，电子处于原子施主状态和2D表面态之间的叠加态。除了确定场和施主深度对电子结构的影响外，该模型还提供了根据Stark特征区分磷和砷施主的基础。该方法还捕捉到了施主势垒和界面势垒中的山谷轨道分裂，这是一个对硅量子比特至关重要的量。这项工作最后详细分析了筛选对供体光谱的影响。
Adiabatic shuttling of single impurity bound electrons to gate-induced surface states in semiconductors has attracted much attention in recent times, mostly in the context of solid-state quantum computer architecture. A recent transport spectroscopy experiment for the first time was able to probe the Stark shifted spectrum of a single donor in silicon buried close to a gate. Here, we present the full theoretical model involving large-scale quantum mechanical simulations that was used to compute the Stark shifted donor states in order to interpret the experimental data. Use of atomistic tight-binding technique on a domain of over a million atoms helped not only to incorporate the full band structure of the host, but also to treat realistic device geometries and donor models, and to use a large enough basis set to capture any number of donor states. The method yields a quantitative description of the symmetry transition that the donor electron undergoes from a three-dimensional Coulomb confined state to a two-dimensional (2D) surface state as the electric field is ramped up adiabatically. In the intermediate field regime, the electron resides in a superposition between the atomic donor states and the 2D surface states. In addition to determining the effect of field and donor depth on the electronic structure, the model also provides a basis to distinguish between a phosphorus and an arsenic donor based on their Stark signature. The method also captures valley-orbit splitting in both the donor well and the interface well, a quantity critical to silicon qubits. The work concludes with a detailed analysis of the effects of screening on the donor spectrum.