Electron Spin Resonance of P Donors in Isotopically Purified Si Detected by Contactless Photoconductivity
Electron Spin Resonance of P Donors in Isotopically Purified
Si
Detected by Contactless Photoconductivity
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非接触光电导检测同位素纯化硅中 P 供体的电子自旋共振
DOI：
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发表时间：
2019
影响因子：
4.6
通讯作者：
J. Morton
中科院分区：
文献类型：
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作者：
Philipp Ross;B. Rose;C. Lo;C. Lo;M. Thewalt;A. Tyryshkin;S. Lyon;J. Morton;J. Morton
用标准的哈恩回波技术测量了在[P]=1014 cm-3，温度为≤4K的同位素纯硅中，束缚在磷施主上的电子自旋的相干时间可达20ms。尽管固态中的电子自旋时间特别长，但它们仍然受到施主电子自旋-自旋相互作用的限制。抑制这种相互作用需要更低的给体浓度，这低于典型ESR光谱仪的检测下限。在这里，我们描述了一种检测磷施主ESR的替代方法，利用光学施主-束缚-激子跃迁提供的自旋到电荷的转换。我们描述了这种方法及其对激光功率的依赖关系，并用它测量了迄今生长的最纯的硅样品之一的相干时间T2=130ms([P]=5×1011 cm-3)。然后，我们使用施主-束缚-激子跃迁的另一种应用对这一结果进行基准测试：在1.7K对[P]=4×1012 cm-3的样品使用传统的ESR检测之前，光学极化施主自旋，并在这种情况下测量T2为350ms。在这两种情况下，t2是在考虑了磁场噪声的影响后获得的，并且使用更稳定(例如，永久)的磁铁可以产生甚至更长的相干时间。
Coherence times of electron spins bound to phosphorus donors have been measured, using a standard Hahn echo technique, to be up to 20 ms in isotopically pure silicon with [P]=1014cm-3 and at temperatures ≤4K. Although such times are exceptionally long for electron spins in the solid state, they are nevertheless limited by donor electron spin-spin interactions. Suppressing such interactions requires even lower donor concentrations, which lie below the detection limit for typical ESR spectrometers. Here we describe an alternative method for phosphorus donor ESR detection, exploiting the spin-to-charge conversion provided by the optical donor-bound-exciton transition. We characterize the method and its dependence on laser power and use it to measure a coherence time of T2=130ms for one of the purest silicon samples grown to date ([P]=5×1011cm-3). We then benchmark this result using an alternative application of the donor-bound-exciton transition: optically polarizing the donor spins before using conventional ESR detection at 1.7 K for a sample with [P]=4×1012cm-3, and measuring in this case a T2 of 350 ms. In both cases, T2 is obtained after accounting for the effects of magnetic field noise, and the use of more stable (e.g., permanent) magnets could yield even longer coherence times.