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Measurement of the roughness of nano-scale surfaces, both unannealed and with limited anneal, by atomic force microscopy.

Seah, M P (2014) Measurement of the roughness of nano-scale surfaces, both unannealed and with limited anneal, by atomic force microscopy. Meas. Sci. Technol., 25 (10). 105001

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Abstract

The roughness and bias measured for surfaces scanned by a parabolic atomic force microscope tip are analysed computationally for surfaces exhibiting a random, Gaussian population of heights, uncorrelated from pixel to pixel. The fraction of the surface for which the probe is in contact is then analysed in detail to show the area fraction of the surface that is, in practice, contacted within a defined tolerance. This shows that it is very difficult to measure much of these surfaces for any significant roughness even though the roughness value may sometimes be approximately correct. The surface is then allowed a limited anneal and the improvement in the validity of the measurement is determined. Annealing removes the very short-range structure and permits more meaningful roughnesses to be determined with a greater fraction of the surface contacted by the probe. This limited anneal may simulate the behaviour of hot atoms incident or impacted by energetic ions and that rapidly cool at the surface. Asymmetric, non-Gaussian height distributions are also analysed and these generate a significantly different measurement bias that can be more sensitive to the tip radius. The height distribution shapes alter with the tip radius so that accurate estimation of the originating height distribution is not possible. Simple equations are provided to describe the effects.

Item Type: Article
Keywords: AFM, atomic force microscopy, depth profiling, roughness, SPM, step heights
Subjects: Nanoscience
Nanoscience > Surface and Nanoanalysis
Identification number/DOI: 10.1088/0957-0233/25/10/105001
Last Modified: 02 Feb 2018 13:14
URI: http://eprintspublications.npl.co.uk/id/eprint/6321

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