Electron spin coherence of silicon vacancies in proton- irradiated 4H-SiC
Electron spin coherence of silicon vacancies in proton- irradiated 4H-SiC
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DOI：
10.1103/physrevb.95.045206
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发表时间：
2017-01-17
影响因子：
3.7
通讯作者：
Carter, S. G.
中科院分区：
文献类型：
--
作者：
Embley, J. S.;Colton, J. S.;Carter, S. G.
本文报道了4 H-SiC中Si空位局域电子态的T-2自旋相干时间。我们的自旋相干性研究包括两个SiC样品，它们用2 MeV质子以不同的注量（10（13）和10（14）cm（-2））辐照，以产生具有独特缺陷浓度的样品。使用光学检测的磁共振和自旋回波，在8至295 K的温度范围内测量每个样品的相干时间。所有的回波实验都是在磁场强度为0.371 T，微波频率为10.49 GHz的条件下进行的。在8 K下获得最长的相干时间，对于10（13）cm（-2）质子辐照的样品为270 +/-61 μ s，对于10（14）cm（-2）样品为104 +/-17 μ s。这两个样品的相干时间显示出不寻常的温度依赖性，特别是，它们随温度下降，直到60 K，然后增加，直到160 K，然后再次下降。在60和160 K之间的这种增加暂时归因于运动的Jahn-Teller效应。10（13）cm（-2）样品的持续较长寿命表明，自旋退相的重要来源可以归因于Si空位之间的偶极-偶极相互作用或质子辐照产生的其他缺陷。对于我们的10（14）cm（-2）样品，缺乏简单的指数衰减表明缺陷自旋的不均匀分布。
We report T-2 spin coherence times for electronic states localized in Si vacancies in 4H-SiC. Our spin coherence study included two SiC samples that were irradiated with 2MeV protons at different fluences (10(13) and 10(14) cm(-2)) in order to create samples with unique defect concentrations. Using optically detected magnetic resonance and spin echo, the coherence times for each sample were measured across a range of temperatures from 8 to 295 K. All echo experiments were done at a magnetic field strength of 0.371 T and a microwave frequency of 10.49 GHz. The longest coherence times were obtained at 8 K, being 270 +/- 61 mu s for the 10(13) cm(-2) proton-irradiated sample and 104 +/- 17 mu s for the 10(14) cm(-2) sample. The coherence times for both samples displayed unusual temperature dependencies; in particular, they decreased with temperature until 60 K, then increased until 160 K, then decreased again. This increase between 60 and 160 K is tentatively attributed to a motional Jahn-Teller effect. The consistently longer lifetimes for the 10(13) cm(-2) sample suggest that a significant source of the spin dephasing can be attributed to dipole-dipole interactions between Si vacancies or with other defects produced by the proton irradiation. The lack of a simple exponential decay for our 10(14) cm(-2) sample indicates an inhomogeneous distribution of defect spins.