title: Improved atomic force microscopy cantilever performance by partial reflective coating.
abstract: Optical beam deflection systems are widely used in cantilever based atomic force microscopy (AFM). Most commercial cantilevers have a reflective metal coating on the detector side to increase the reflectivity in order to achieve a high signal on the photodiode. Although the reflective coating is usually much thinner than the cantilever, it can still significantly contribute to the damping of the cantilever, leading to a lower mechanical quality factor (Q-factor). In dynamic mode operation in high vacuum, a cantilever with a high Q-factor is desired in order to achieve a lower minimal detectable force. The reflective coating can also increase the low-frequency force noise. In contact mode and force spectroscopy, a cantilever with minimal low-frequency force noise is desirable. We present a study on cantilevers with a partial reflective coating on the detector side. For this study, soft (≈0.01 N/m) and stiff (≈28 N/m) rectangular cantilevers were used with a custom partial coating at the tip end of the cantilever. The Q-factor, the detection and the force noise of fully coated, partially coated and uncoated cantilevers are compared and force distance curves are shown. Our results show an improvement in low-frequency force noise and increased Q-factor for the partially coated cantilevers compared to fully coated ones while maintaining the same reflectivity, therefore making it possible to combine the best of both worlds.
authors.affiliation: Department of Physics, McGill University, Montreal, Quebec, H3A 2T8, Canada.
authors.forename: Zeno
authors.initials: Z
authors.lastname: Schumacher
authors.affiliation: Department of Physics, McGill University, Montreal, Quebec, H3A 2T8, Canada.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Miyahara
authors.affiliation: NanoWorld AG, Neuchâtel, 2002, Switzerland.
authors.forename: Laure
authors.initials: L
authors.lastname: Aeschimann
authors.affiliation: Department of Physics, McGill University, Montreal, Quebec, H3A 2T8, Canada.
authors.forename: Peter
authors.initials: P
authors.lastname: Grütter
keywords: Q-factor; cantilever; force noise; partial coating