Berlin 2018 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 1: Layer Properties: Electronic, Optical and Mechanical

DS 1.5: Vortrag

Montag, 12. März 2018, 10:30–10:45, H 0111

Quantitative AM-FM Mode for Fast, Versatile Imaging of Nanoscale Elastic Modulus — •Florian Johann, Roger Proksch, Marta Kocun, and Ted Limpoco — Oxford Instruments (Asylum Research), Santa Barbara, USA

Nanoscale information on mechanical properties is critical for many advanced materials and nanotechnology applications. Atomic Force Microscopy (AFM) techniques for probing mechanical properties of samples in the nanometer range have emerged over the past decades.

Amplitude-modulated AFM (AM-AFM), also known as tapping mode, is a proven, reliable and gentle imaging method with widespread applications. Previously, the contrast in AM-AFM has been difficult to quantify. Here, we introduce AM-FM imaging, which combines the features and benefits of normal tapping mode with quantitative and high sensitivity of frequency modulated (FM) mode. Briefly, the topographic feedback operates in AM mode while the second resonant mode drive frequency is adjusted on resonance. With this approach, frequency feedback and topographic feedback are decoupled, allowing much more stable, robust operation. The FM image returns a quantitative value of the frequency shift that depends on the sample stiffness and can be applied to a variety of physical models.