A versatile LabVIEW and FPGA-based scanned probe microscope for in-operando electronic device characterization

TL;DR

This paper presents a versatile, FPGA-based scanned probe microscope integrated with LabVIEW for in-operando electronic device characterization, enabling simultaneous force imaging and electrical measurements with real-time control and flexible software interfaces.

Contribution

The development of a flexible, FPGA and LabVIEW-based SPM system capable of combined force imaging and electrical transport measurements in real-time is a novel contribution.

Findings

Successful electrostatic force microscopy of a graphene FET.

Real-time sensitive cantilever frequency-shift detection.

Integrated imaging of transport response to localized perturbations.

Abstract

Understanding the complex properties of electronic and spintronic devices at the micro- and nano-scale is a topic of intense current interest as it becomes increasingly important for scientific progress and technological applications. In-operando characterization of such devices by scanned probe techniques is particularly well-suited for the microscopic study of these properties. We have developed a scanned probe microscope (SPM) which is capable of both standard force imaging (atomic, magnetic, electrostatic) and simultaneous electrical transport measurements. We utilize flexible and inexpensive FPGA (field programmable gate array) hardware and a custom software framework developed in National Instrument's LabVIEW environment to perform the various aspects of microscope operation and device measurement. The FPGA-based approach enables sensitive, real-time cantilever frequency-shift detection. Using this system, we demonstrate electrostatic force microscopy of an electrically-biased graphene FET device. The combination of SPM and electrical transport also enables imaging of the transport response to a localized perturbation provided by the scanned cantilever tip. Facilitated by the broad presence of LabVIEW in the experimental sciences and the openness of our software solution, our system permits a wide variety of combined scanning and transport measurements by providing standardized interfaces and flexible access to all aspects of a measurement (input and output signals, and processed data). Our system also enables precise control of timing (synchronization of scanning and transport operations) and implementation of sophisticated feedback protocols, and thus should be broadly interesting and useful to practitioners in the field.