Fast, high-resolution atomic force microscopy using a quartz tuning fork as actuator and sensor

Abstract

We report a new method of achieving tip-sample distance regulation in an atomic force microscope ͑AFM͒. A piezoelectric quartz tuning fork serves as both actuator and sensor of tip-sample interactions, allowing tip-sample distance regulation without the use of a diode laser or dither piezo. Such a tuning fork has a high spring constant so a dither amplitude of only 0.1 nm may be used to perform AFM measurements. Tuning-fork feedback is shown to operate at a noise level as low as that of a cantilever-based AFM. Using phase-locked-loop control to track excursions in the resonant frequency of a 32 kHz tuning fork, images are acquired at scan rates which are fast enough for routine AFM measurements. Magnetic force microscopy using tuning-fork feedback is demonstrated.

High-speed force sensor for force microscopy and profilometry utilizing a quartz tuning fork

“…Güethner et al 7 have used tuning forks as a force sensor in acoustic near field microscopy and Karrai et al 8 have used a tuning fork to control the distance between the optical fiber and the surface in a scanning near-field-optical microscope. Recently, Edwards et al 9 have demonstrated a faster mode using a phase-locked-loop detector.…”

“…16 The acquisition speed was 12 lines per second ͑lps͒ and the width of the image is 9.6 m, thus the scanning speed is 230 m/ s-100 times faster than in previous implementations. 9 Figure 5 presents an image of a calibration grating. Here, the tip of the QPS is a small crystal of sapphire ͑approx.…”

Atomic resolution on Si(111)-(7×7) by noncontact atomic force microscopy with a force sensor based on a quartz tuning fork

“…Tuning forks have been used in scanning probe microscopes before. [9][10][11][12][13][14][15][16][17] However, atomic resolution has not been reported so far.…”

Kelvin probe spectroscopy of a two-dimensional electron gas below 300 mK

“…Scanning is performed with an electrochemically etched metallic tip attached to the end face of one prong of a piezoelectric quartz tuning fork [8,9,10,11,12].…”