Double quartz tuning fork sensor for low temperature atomic force and scanning tunneling microscopy

2004 ◽  
Vol 75 (7) ◽  
pp. 2446-2450 ◽  
Author(s):  
M. Heyde ◽  
M. Kulawik ◽  
H.-P. Rust ◽  
H.-J. Freund
Keyword(s):  
Low Temperature ◽  
Scanning Tunneling Microscopy ◽  
Tuning Fork ◽  
Quartz Tuning Fork ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Atomic Force

scholarly journals Development and Comparative Analysis of Electrochemically Etched Tungsten Tips for Quartz Tuning Fork Sensor

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 286
Author(s):  
Ashfaq Ali ◽  
Naveed Ullah ◽  
Asim Ahmad Riaz ◽  
Muhammad Zeeshan Zahir ◽  
Zuhaib Ali Khan ◽  
...  
Keyword(s):  
Tuning Fork ◽  
Mechanical Stability ◽  
Electrochemical Etching ◽  
Research Work ◽  
Cone Angle ◽  
Quartz Tuning Fork ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
High Quality ◽  
Scanning Electron

Quartz Tuning Fork (QTF) based sensors are used for Scanning Probe Microscopes (SPM), in particular for near-field scanning optical microscopy. Highly sharp Tungsten (W) tips with larger cone angles and less tip diameter are critical for SPM instead of platinum and iridium (Pt/Ir) tips due to their high-quality factor, conductivity, mechanical stability, durability and production at low cost. Tungsten is chosen for its ease of electrochemical etching, yielding high-aspect ratio, sharp tips with tens of nanometer end diameters, while using simple etching circuits and basic electrolyte chemistry. Moreover, the resolution of the SPM images is observed to be associated with the cone angle of the SPM tip, therefore Atomic-Resolution Imaging is obtained with greater cone angles. Here, the goal is to chemically etch W to the smallest possible tip apex diameters. Tips with greater cone angles are produced by the custom etching procedures, which have proved superior in producing high quality tips. Though various methods are developed for the electrochemical etching of W wire, with a range of applications from scanning tunneling microscopy (SPM) to electron sources of scanning electron microscopes, but the basic chemical etching methods need to be optimized for reproducibility, controlling cone angle and tip sharpness that causes problems for the end users. In this research work, comprehensive experiments are carried out for the production of tips from 0.4 mm tungsten wire by three different electrochemical etching techniques, that is, Alternating Current (AC) etching, Meniscus etching and Direct Current (DC) etching. Consequently, sharp and high cone angle tips are obtained with required properties where the results of the W etching are analyzed, with optical microscope, and then with field emission scanning electron microscopy (FE-SEM). Similarly, effects of varying applied voltages and concentration of NaOH solution with comparison among the produced tips are investigated by measuring their cone angle and tip diameter. Moreover, oxidation and impurities, that is, removal of contamination and etching parameters are also studied in this research work. A method has been tested to minimize the oxidation on the surface and the tips were characterized with scanning electron microscope (SEM).

scholarly journals Simultaneous current, force and dissipation measurements on the Si(111) 7×7 surface with an optimized qPlus AFM/STM technique

2012 ◽  
Vol 3 ◽  
pp. 249-259 ◽  
Author(s):  
Zsolt Majzik ◽  
Martin Setvín ◽  
Andreas Bettac ◽  
Albrecht Feltz ◽  
Vladimír Cháb ◽  
...  
Keyword(s):  
Cross Talk ◽  
Tuning Fork ◽  
Tunneling Current ◽  
Quartz Tuning Fork ◽  
Scanning Tunneling ◽  
Experimental Setup ◽  
Force Microscopy ◽  
Atomic Force ◽  
Force Signal ◽  
Reported Data

We present the results of simultaneous scanning-tunneling and frequency-modulated dynamic atomic force microscopy measurements with a qPlus setup. The qPlus sensor is a purely electrical sensor based on a quartz tuning fork. If both the tunneling current and the force signal are to be measured at the tip, a cross-talk of the tunneling current with the force signal can easily occur. The origin and general features of the capacitive cross-talk will be discussed in detail in this contribution. Furthermore, we describe an experimental setup that improves the level of decoupling between the tunneling-current and the deflection signal. The efficiency of this experimental setup is demonstrated through topography and site-specific force/tunneling-spectroscopy measurements on the Si(111) 7×7 surface. The results show an excellent agreement with previously reported data measured by optical interferometric deflection.

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