3rd Institute of Physics, Research Center SCoPE and IQST, University of Stuttgart, Stuttgart 70569, Germany.
Institute of Electron Devices and Circuits, University of Ulm, Ulm 89081, Germany.
Nat Commun. 2017 May 17;8:15409. doi: 10.1038/ncomms15409.
Atomic-size spin defects in solids are unique quantum systems. Most applications require nanometre positioning accuracy, which is typically achieved by low-energy ion implantation. A drawback of this technique is the significant residual lattice damage, which degrades the performance of spins in quantum applications. Here we show that the charge state of implantation-induced defects drastically influences the formation of lattice defects during thermal annealing. Charging of vacancies at, for example, nitrogen implantation sites suppresses the formation of vacancy complexes, resulting in tenfold-improved spin coherence times and twofold-improved formation yield of nitrogen-vacancy centres in diamond. This is achieved by confining implantation defects into the space-charge layer of free carriers generated by a boron-doped diamond structure. By combining these results with numerical calculations, we arrive at a quantitative understanding of the formation and dynamics of the implanted spin defects. These results could improve engineering of quantum devices using solid-state systems.
固体中的原子级自旋缺陷是独特的量子系统。大多数应用都需要纳米级的定位精度，这通常可以通过低能离子注入来实现。该技术的一个缺点是会造成明显的晶格残余损伤，从而降低量子应用中自旋的性能。本文展示了注入诱导缺陷的电荷状态会极大地影响热退火过程中晶格缺陷的形成。例如，在氮注入位点上对空位进行充电会抑制空位复合物的形成，从而使金刚石中氮空位中心的自旋相干时间提高十倍，形成产率提高两倍。这是通过将注入缺陷限制在由掺硼金刚石结构产生的自由载流子的空间电荷层中来实现的。通过将这些结果与数值计算相结合，我们对注入自旋缺陷的形成和动力学有了定量的理解。这些结果可以改进使用固态系统的量子器件的工程设计。
