Characterization of atomic force microscope probes at low temperatures

Different types of atomic force microscopy ~AFM! probes were characterized under ultrahigh vacuum conditions and at low temperatures. Properties of AFM probes, such as the resonance frequency, the spring constant and quality factor of cantilevers, depend on temperature. A typical shift in the resonance frequency as a function of temperature was observed for all kinds of cantilevers studied. This was related to the change in temperature of Young's modulus of the cantilever material. Moreover, force-distance curves acquired at low temperatures and on different substrates, elucidate the importance of the hydrophobicity of the sample surface and that of the tips for lowering adhesion forces. Finally, all of the probes were imaged in a scanning electron microscope as a function of the temperature. A bending of the coated cantilever at low temperatures was observed, which explains the peculiar force-distance curves. As a consequence, the use of uncoated cantilevers for low-temperature applications is recommended.