X-Ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA.
Proc Natl Acad Sci U S A. 2013 Aug 13;110(33):13250-4. doi: 10.1073/pnas.1220106110. Epub 2013 Jul 29.
We report the results of highly sensitive transmission X-ray scattering measurements performed at the Advanced Photon Source, Argonne National Laboratory, on nearly fully dense high-purity amorphous-silicon (a-Si) samples for the purpose of determining their degree of hyperuniformity. A perfectly hyperuniform structure has complete suppression of infinite-wavelength density fluctuations, or, equivalently, the structure factor S(q→0) = 0; the smaller the value of S(0), the higher the degree of hyperuniformity. Annealing was observed to increase the degree of hyperuniformity in a-Si where we found S(0) = 0.0075 (±0.0005), which is significantly below the computationally determined lower bound recently suggested by de Graff and Thorpe [de Graff AMR, Thorpe MF (2010) Acta Crystallogr A 66(Pt 1):22-31] based on studies of continuous random network models, but consistent with the recently proposed nearly hyperuniform network picture of a-Si. Increasing hyperuniformity is correlated with narrowing of the first diffraction peak and extension of the range of oscillations in the pair distribution function.
我们报告了在阿贡国家实验室高级光子源进行的高灵敏度透射 X 射线散射测量的结果，这些测量是针对近乎完全致密的高纯非晶硅（a-Si）样品进行的，目的是确定它们的超均匀度程度。完美的超均匀结构完全抑制了无限波长密度涨落，或者等效地说，结构因子 S(q→0) = 0；S(0)的值越小，超均匀度越高。我们发现，退火会增加 a-Si 的超均匀度，其中我们发现 S(0) = 0.0075（±0.0005），这明显低于 de Graaff 和 Thorpe 最近基于连续随机网络模型研究提出的计算确定的下限[de Graaff AMR, Thorpe MF (2010) Acta Crystallogr A 66(Pt 1):22-31]，但与最近提出的 a-Si 的近乎超均匀网络图像一致。超均匀度的增加与第一衍射峰的变窄和对分布函数的振荡范围的扩展相关。
