Detection of Microelectromechanical System Acoustics via Scanning Tunneling Microscopy.

Area of Science:

• Nanotechnology
• Materials Science
• Mechanical Engineering

Background:

• Scanning tunneling microscopy (STM) and microelectromechanical systems (MEMS) operate at different length scales.
• Conventional readout methods for high-Q resonators at cryogenic temperatures introduce unwanted dissipation and heating.
• Bridging these scales is crucial for precise force measurements in sensitive systems.

Purpose of the Study:

• To utilize STM as a minimally invasive actuator and detector for high-aspect-ratio MEMS resonators.
• To overcome limitations of optical and electrical readout methods in cryogenic environments.
• To achieve picometer spatial precision in measuring acoustic modes of high-Q membranes.

Main Methods:

• Employing an STM tip for both actuation and detection of MEMS resonators.
• Implementing three detection modalities: homodyne readout, rapid measurements, and near-nonperturbative operation.
• Operating the system without optical readout or capacitive coupling to minimize perturbation.

Main Results:

• Successfully resolved acoustic modes of millimeter-scale, high-Q membranes with picometer precision.
• Demonstrated minimal back-action and heating due to the localized, low-dissipation tunneling junction.
• Achieved force sensitivity on the order of a few piconewtons across various measurement conditions.

Conclusions:

• Established STM as a broadband, surface-localized nanomechanical detector suitable for cryogenic and high-magnetic-field environments.
• Expanded the experimental toolbox for nanomechanics, enabling precision measurements in suspended systems.
• Paved the way for studying phenomena like Casimir interactions and hybrid electromechanical devices with unprecedented sensitivity.