The effect of wafer curvature on x-ray rocking curves from gallium nitride films
The effect of wafer curvature on x-ray rocking curves from gallium nitride films
复制标题
DOI：
10.1063/1.2913514
复制
发表时间：
2008-05
影响因子：
3.2
通讯作者：
M. Moram;M. E. Vickers;M. Kappers;C. Humphreys
中科院分区：
文献类型：
--
作者：
M. Moram;M. E. Vickers;M. Kappers;C. Humphreys
X 射线摇摆曲线的半峰全宽 (FWHM) 通常用作薄膜晶体质量的衡量标准。在本文中，晶圆曲率对从 2 英寸获得的 X 射线摇摆曲线（ω 扫描）的影响。讨论了0001取向蓝宝石晶片和在这种晶片上生长的外延0001取向GaN薄膜。光束高度降低可以限制对称和非对称反射的曲率相关效应；这些效应对于低位错密度 GaN 薄膜通常很重要。由于斜对称几何形状中 X 射线束照射区域的形状，光束宽度减小反而是适当的，但这仍然低估了使用开放探测器获得的 ω-FWHM 值，高估了使用分析仪获得的 ω-FWHM 值。因此，来自弯曲样本的偏斜对称 ω-FWHM 值通常不可靠。此外，在存在显着曲率的情况下，使用 ω 扫描的 Williamson-Hall 分析变得不可靠。变化在...
The full width at half maximum (FWHM) of x-ray rocking curves is often used as a measure of the crystalline quality of thin films. In this paper, the effects of wafer curvature on the x-ray rocking curves (ω-scans) obtained from a 2in. 0001-oriented sapphire wafer and an epitaxial 0001-oriented GaN film grown on such a wafer are discussed. Beam height reduction can limit curvature-related effects for symmetric and asymmetric reflections; these effects are generally significant for low dislocation density GaN films. Due to the shape of the area illuminated by the x-ray beam in the skew symmetric geometry, beam width reduction is instead appropriate, but this still gives an underestimate of ω-FWHM values obtained with an open detector and an overestimate of ω-FWHM values obtained with an analyzer. Therefore, skew symmetric ω-FWHM values from curved samples are often unreliable. Additionally, Williamson–Hall analysis using ω-scans is rendered unreliable in the presence of significant curvature. Variations in...