Past exam of the MPhil in micro- and nanotechnology enterprise course of the University of Cambridge / 2023 / Paper 1 / Section A(i) / 2 / iii / Solution 2026-10-20
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An attached particle changes the effective tip shape, potentially creating a second contact apex. The image can then show duplicated or broadened copies of surface features, shifted edge positions and altered apparent roughness: a double-tip artefact or more general AFM tip-convolution artefact. Detachment can produce a sudden line-to-line change in that image kernel, so a region may abruptly recover a sharper profile. A change that follows the probe state or scan history should not be interpreted as a real reconstruction of the semiconductor surface.
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