We analyze the valley composition of one electron bound to a shallow donorclose to a Si/barrier interface as a function of an applied electric field. Afull six-valley effective mass model Hamiltonian is adopted. For low fields,the electron ground state is essentially confined at the donor. At high fieldsthe ground state is such that the electron is drawn to the interface, leavingthe donor practically ionized. Valley splitting at the interface occurs due tothe valley-orbit coupling, V_vo^I = |V_vo^I| e^{i theta}. At intermediateelectric fields, close to a characteristic shuttling field, the electron statesmay constitute hybridized states with valley compositions different from thedonor and the interface ground states. The full spectrum of energy levels showscrossings and anti-crossings as the field varies. The degree of levelrepulsion, thus the width of the anti-crossing gap, depends on the relativevalley compositions, which vary with |V_vo^I|, theta and the interface-donordistance. We focus on the valley configurations of the states involved in thedonor-interface tunneling process, given by the anti-crossing of the threelowest eigenstates. A sequence of two anti-crossings takes place and thecomplex phase theta affects the symmetries of the eigenstates and levelanti-crossing gaps. We discuss the implications of our results on the practicalmanipulation of donor electrons in Si nanostructures.
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机译：我们分析了一个电子的谷组成，该电子绑定到一个靠近Si /势垒界面的浅施主，作为施加电场的函数。采用全六谷有效质量模型哈密顿量。对于低场，电子基态基本上局限于施主。在高场，基态使电子被吸引到界面，使施主几乎被电离。由于波谷-轨道耦合，V_vo ^ I = | V_vo ^ I |，在界面处发生波谷分裂。 e ^ {i theta}。在接近特征穿梭场的中间电场处，电子态可以构成杂化态，其谷组成不同于施主和界面基态。能级的全谱图显示随着场的变化，交叉和反交叉。水平排斥的程度，即反交叉间隙的宽度，取决于相对谷组成，相对谷组成随| V_vo ^ I |，θ和界面供体距离而变化。我们着眼于三个最低本征态的反交叉，给出了供体界面隧穿过程所涉及的各州的谷底构型。发生了两个反交叉的序列，复杂的相θ影响了本征态的对称性和水平的反交叉间隙。我们讨论了我们的结果对Si纳米结构中施主电子的实际操纵的意义。
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