Kaganer Vladimir M, Konovalov Oleg V, Fernández-Garrido Sergio
Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117 Berlin, Germany.
European Synchrotron Radiation Facility, 71 avenue des Martyrs, 38043 Grenoble, France.
Acta Crystallogr A Found Adv. 2021 Jan 1;77(Pt 1):42-53. doi: 10.1107/S205327332001548X. Epub 2021 Jan 5.
Small-angle X-ray scattering from GaN nanowires grown on Si(111) is measured in the grazing-incidence geometry and modelled by means of a Monte Carlo simulation that takes into account the orientational distribution of the faceted nanowires and the roughness of their side facets. It is found that the scattering intensity at large wavevectors does not follow Porod's law I(q) ∝ q. The intensity depends on the orientation of the side facets with respect to the incident X-ray beam. It is maximum when the scattering vector is directed along a facet normal, reminiscent of surface truncation rod scattering. At large wavevectors q, the scattering intensity is reduced by surface roughness. A root-mean-square roughness of 0.9 nm, which is the height of just 3-4 atomic steps per micrometre-long facet, already gives rise to a strong intensity reduction.
对生长在Si(111)上的GaN纳米线进行小角X射线散射测量，采用掠入射几何构型，并通过蒙特卡罗模拟进行建模，该模拟考虑了多面纳米线的取向分布及其侧面的粗糙度。研究发现，大波矢处的散射强度并不遵循Porod定律I(q) ∝ q。强度取决于侧面相对于入射X射线束的取向。当散射矢量沿面法线方向时强度最大，这让人联想到表面截断杆散射。在大波矢q处，散射强度因表面粗糙度而降低。均方根粗糙度为0.9 nm，这仅相当于每微米长的面有3 - 4个原子台阶的高度，就已经导致强度大幅降低。
