Illuminating a silicon cantilever of an atomic force microscope with a focused laser beam creates heat that can be funneled into a nanoscale area at the apex of its tip. To characterize the heating dynamics and measure the temperature of the tip, a Raman scattering pump-and-probe method is used. It is found that at the apex of the tip the intensity of the Raman Stokes and anti-Stokes components are significantly enhanced relative to those obtained on a bulk silicon sample. Modeling the temperature rise at the tip of the cantilever by a closed-form analytical expression gives good agreement with the Raman measurements. This model can be used to design the structure of the cantilever so that the heat delivery to its tip is optimized. Such an optimized cantilever can potentially be used in high-density, heat-assisted magnetic recording, optical data storage using phase-change media and thermomechanical recording systems, for example, where nanoscale heated regions are of importance.

We report on the use of Kelvin probe force microscopy in measuring the shift of the contact potential difference of micron-scale areas. The experimental results provide important information required for understanding and modeling the electrical characteristics of chemically sensitive field-effect transistors (ChemFETs). The temporal evolution in the shift of the contact potential difference of chemically sensitive monolayers of free-base porphyrin and zinc-porphyrin on exposure to pyridine gas was studied and their different behavior observed. The Kelvin probe force microscopy data on nanometer-scale areas were in agreement with those obtained with a conventional Kelvin probe on centimeter-scale areas. The accuracy of the measured shift in contact potential difference upon exposure to trace amounts of gas indicates the utility of Kelvin probe force microscopy as a means to characterize the operation of exposed-gate ChemFETs.

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