Versatile low-temperature atomic force microscope with in situ piezomotor controls, charge-coupled device vision, and tip-gated transport measurement capability

A versatile cryogenic (5 K) ultrahigh-vacuum (UHV) atomic force microscope (AFM) with tip-gated transport measurement capability has been developed. Using high-resolution (<1.5μm) plan-view charge-coupled device (CCD) optics, and three planar piezomotors we achieved visually guided in situ alignments of a sample position with respect to the AFM tip, and the laser beam position with respect to the cantilever and the quadrant photodiode. We made optical fiber feedthroughs and a laser lens assembly to bring external laser light and CCD illuminating light onto the cantilever and the sample. A sample holder with an embedded temperature sensor and eight transport electrodes is detachably mounted on a piezotube scanner. The generic cantilever mount can be easily replaced with a tuning-fork mount or a piezoresistive cantilever mount for experiments where stray laser light should be avoided. To our knowledge, this is the first Dewar-immersion type cryogenic AFM with laser beam deflection sensing capability and high-resolution plan-view CCD optics.