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Practice detailsLocal elasticity imaging. See practice details of topography acquisition, ZnSSe/GaAs laser structure. We excited the piezoactuator of a cantilever and measured the amplitude-frequency characteristic of the cantilever, to find a well-defined resonant peak. In contact mode the cantilever (e.g. we used soft cantilevers CSC12 with long beams and typical frequencies of free resonance 10-30 kHz) is fixed from both ends, and the resonant peaks are usually observed in the frequency domain of few hundredths kHz. The signal of vibration amplitude is proportional to the tip-surface contact stiffness. The studied sample exhibits strongly non-uniform topography with height variations up to several hundredths nanometers. Therefore in our case the signal depends mainly on the effective curvature of tip-sample contact and was used to enhance resolution of small surface features. Specific parameters of the scan can be found in f7.opt and f7.mdt. AFM images are obtained by commercial SPM P4 with CSC12 cantilevers. Additional information about laser structures were received with usage of Contact EFM, Kelvin mode.
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