Roark S E, Semin D J, Rowlen K L
Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309.
Anal Chem. 1996 Feb 1;68(3):473-80. doi: 10.1021/ac950909d.
The reliability of an image analysis algorithm for atomic force microscopy (AFM) of thin metal films was evaluated by comparison with manual analysis of images and transmission electron micrographs of Ag films deposited on Formvar-coated Cu grids. In order to extract quantitative nanostructural information using the algorithm discussed herein, the optimal fitting parameters were found to be low-pass filtering to reject high-frequency noise, a 5 × 5 point grid for identification of particle maxima, and a linear least-squares fit to a hemispheroidal model of particle shape. Metal particle dimensions were defined from the height and radius of the hemispheroid fit. Due to the close spacing of particles in these Ag films, tip geometry causes the greatest error in the height measurements, rather than width measurements. In addition, the effect of scanning parameters such as scan rate and size, applied load, and humidity on particle count and dimensions was examined. Increasing the scan rate reduced the number of resolvable Ag particles, decreased the apparent particle height, and increased the apparent particle radius. Under conditions of low capillary force, a net repulsive force of ∼19 nN resulted in subtle tip-induced changes in the Ag surface morphology. The Ag film surface was damaged at a net repulsive force of ∼23 nN. At slow scan rates, the moisture layer did not significantly affect the quality of the AFM images obtained over a broad relative humidity range. Finally, the Ag surface structure was found to be very homogeneous over a relatively large area.
通过与对沉积在福尔马膜涂层铜网上的银膜图像和透射电子显微镜图像进行人工分析相比较，评估了一种用于薄金属膜原子力显微镜（AFM）图像分析算法的可靠性。为了使用本文讨论的算法提取定量的纳米结构信息，发现最佳拟合参数为：采用低通滤波以去除高频噪声；使用5×5点网格来识别颗粒最大值；对颗粒形状的半球模型进行线性最小二乘拟合。金属颗粒尺寸由半球拟合的高度和半径确定。由于这些银膜中颗粒间距紧密，针尖几何形状在高度测量中造成的误差最大，而非宽度测量。此外，还研究了扫描速率和尺寸、外加负载及湿度等扫描参数对颗粒计数和尺寸的影响。提高扫描速率会减少可分辨的银颗粒数量，降低表观颗粒高度，并增加表观颗粒半径。在低毛细力条件下，约19 nN的净排斥力导致银表面形态出现细微的针尖诱导变化。当净排斥力达到约23 nN时，银膜表面会受到损伤。在慢扫描速率下，在较宽的相对湿度范围内，水分层对获得的AFM图像质量没有显著影响。最后，发现银表面结构在相对较大的区域内非常均匀。
