Dhomkar Siddharth, Zangara Pablo R, Henshaw Jacob, Meriles Carlos A
Department of Physics, CUNY-City College of New York, New York, New York 10031, USA.
CUNY-Graduate Center, New York, New York 10016, USA.
Phys Rev Lett. 2018 Mar 16;120(11):117401. doi: 10.1103/PhysRevLett.120.117401.
Point defects in wide-band-gap semiconductors are emerging as versatile resources for nanoscale sensing and quantum information science, but our understanding of the photoionization dynamics is presently incomplete. Here, we use two-color confocal microscopy to investigate the dynamics of charge in type 1b diamond hosting nitrogen-vacancy (NV) and silicon-vacancy (SiV) centers. By examining the nonlocal fluorescence patterns emerging from local laser excitation, we show that, in the simultaneous presence of photogenerated electrons and holes, SiV (NV) centers selectively transform into the negative (neutral) charge state. Unlike NVs, 532 nm illumination ionizes SiV^{-} via a single-photon process, thus hinting at a comparatively shallower ground state. In particular, slower ionization rates at longer wavelengths suggest the latter lies approximately ∼1.9 eV below the conduction band minimum. Building on the above observations, we demonstrate on-demand SiV and NV charge initialization over large areas via green laser illumination of variable intensity.
宽带隙半导体中的点缺陷正成为纳米级传感和量子信息科学的通用资源，但我们目前对光电离动力学的理解并不完整。在这里，我们使用双色共聚焦显微镜来研究含有氮空位（NV）和硅空位（SiV）中心的1b型金刚石中的电荷动力学。通过检查局部激光激发产生的非局部荧光模式，我们表明，在同时存在光生电子和空穴的情况下，SiV（NV）中心选择性地转变为负（中性）电荷状态。与NVs不同，532 nm光照通过单光子过程使SiV⁻电离，因此暗示其基态相对较浅。特别是，在较长波长下较慢的电离速率表明后者位于导带最小值以下约1.9 eV处。基于上述观察结果，我们通过可变强度的绿色激光照射，在大面积上演示了按需进行的SiV和NV电荷初始化。
