Atomic resolution ultrafast scanning tunneling microscope with scan rate breaking the resonant frequency of a quartz tuning fork resonator

Abstract

We present an ultra-fast scanning tunneling microscope with atomic resolution at 26 kHz scan rate which surpasses the resonant frequency of the quartz tuning fork resonator used as the fast scan actuator. The main improvements employed in achieving this new record are (1) fully low voltage design (2) independent scan control and data acquisition, where the tuning fork (carrying a tip) is blindly driven to scan by a function generator with the scan voltage and tunneling current (I(T)) being measured as image data (this is unlike the traditional point-by-point move and measure method where data acquisition and scan control are switched many times).

Flexure Structural Scanner of Tip Scan Type for High-speed Scanning Tunneling Microscopy

“…Therefore, various efforts have been made to increase the scan speed [3−6]. These efforts have led to fast imaging for Si(111), O/Ru(0001), and highly oriented pyrolytic graphite (HOPG) [3,7,8].…”

Postprocessing Algorithm for Driving Conventional Scanning Tunneling Microscope at Fast Scan Rates

“…The invention of the scanning tunneling microscopy (STM) revolutionized the study of nanoscale and atomic scale surface structures and properties [ 1 , 2 ]. However, STM has rarely been considered a real-time method because of its slow scanning rate compared to most dynamic processes on a surface [ 3 ]. This has severely limited its application to the study of most dynamic processes on surfaces such as surface diffusion, phase transitions, self-assembly phenomena, film growth and etching, chemical reactions, and conformational changes of molecules.…”

“…This has severely limited its application to the study of most dynamic processes on surfaces such as surface diffusion, phase transitions, self-assembly phenomena, film growth and etching, chemical reactions, and conformational changes of molecules. Raising the scan rate of scanning probes has been the objective of intense research efforts in the past decades [ 3 – 5 ], with most of the efforts focused on hardware improvements. On the other hand, researchers have also applied other techniques to utilize conventional, slow scan STM to study dynamic processes.…”

“…But the constant current mode is slow, due to more time required by the piezoelectric movements to register the height change. The time to complete a measurement for each pixel position is about 2 msec for a typical equipment and approaches 0.1 msec for a top-of-line setup [ 3 – 5 ].…”

Quartz tuning fork-based conductive atomic force microscope with glue-free solid metallic tips

“…The studies cover the fabrication of the tip [14] and the remaining parts of the setup [15,16], and include validation tests [17,18]. In the published systems, the QTF sensors usually work in a Qplus configuration: one of the QTF prongs is clamped while the QTF is excited mechanically.…”