Observation of Contact Potential Difference (CPD) on Semiconducter Surface using Ultrahigh Vacuum Scanning Kelvin Probe Force Microscope (UHV SKPM)

2001 ◽  
Vol 7 (S2) ◽  
pp. 864-865
Author(s):  
S Kitamura ◽  
K Suzuki ◽  
C B Mooney
Keyword(s):  
Semiconductor Device ◽  
Dopant Concentration ◽  
Contact Potential Difference ◽  
Two Dimensions ◽  
Potential Difference ◽  
Lateral Resolution ◽  
Kelvin Probe ◽  
Contact Potential ◽  
Contact Mode ◽  
Scanning Kelvin Probe

The scanning Kelvin probe force microscope (SKPM) is a member of the scanning probe microscope (SPM) family, and was derived from the non-contact atomic force microscope (NCAFM) technique. The contact potential difference (CPD) originating from the work function difference between the tip and sample surfaces can be measured using SKPM with simultaneous observation of the topography image. Using SKPM the surface of semiconductor device has been observed to measure the dopant concentration as the CPD difference in two dimensions. Most of the SKPM measurements are acquired in the atmosphere. The lateral resolution is achieved less than 100 nm.On the other hand, Scanning capacitance microscope (SCM) of contact mode is now most popular method to measure the dopant concentration in semiconductor device. However, the lateral resolution of SCM is limited, because of the fact that the contact mode cannot achieve a true atomic resolution, the fact that the capacitance is measured through the insulating layer on surface, and the fact that the tip and sample is damaged by the high electric field to be applied between the tip and sample. So SCM never achieves the atomic level resolution.

scholarly journals Coupled Investigation of Contact Potential and Microstructure Evolution of Ultra-Thin AlOx for Crystalline Si Passivation

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1803
Author(s):  
Zhen Zheng ◽  
Junyang An ◽  
Ruiling Gong ◽  
Yuheng Zeng ◽  
Jichun Ye ◽  
...  
Keyword(s):  
Structural Changes ◽  
Silicon Oxide ◽  
Crystalline Silicon ◽  
Contact Potential Difference ◽  
Potential Difference ◽  
Kelvin Probe ◽  
Contact Potential ◽  
Carrier Lifetimes ◽  
Transmission Electron ◽  
Effective Carrier

In this work, we report the same trends for the contact potential difference measured by Kelvin probe force microscopy and the effective carrier lifetime on crystalline silicon (c-Si) wafers passivated by AlOx layers of different thicknesses and submitted to annealing under various conditions. The changes in contact potential difference values and in the effective carrier lifetimes of the wafers are discussed in view of structural changes of the c-Si/SiO2/AlOx interface thanks to high resolution transmission electron microscopy. Indeed, we observed the presence of a crystalline silicon oxide interfacial layer in as-deposited (200 °C) AlOx, and a phase transformation from crystalline to amorphous silicon oxide when they were annealed in vacuum at 300 °C.

scholarly journals Imaging the surface potential at the steps on the rutile TiO2(110) surface by Kelvin probe force microscopy

2019 ◽  
Vol 10 ◽  
pp. 1228-1236 ◽  
Author(s):  
Masato Miyazaki ◽  
Huan Fei Wen ◽  
Quanzhen Zhang ◽  
Yuuki Adachi ◽  
Jan Brndiar ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Surface Potential ◽  
Active Sites ◽  
Contact Potential Difference ◽  
Kelvin Probe Force Microscopy ◽  
Potential Difference ◽  
Kelvin Probe ◽  
Contact Potential ◽  
Force Microscopy ◽  
First Time

Although step structures have generally been considered to be active sites, their role on a TiO2 surface in catalytic reactions is poorly understood. In this study, we measured the contact potential difference around the steps on a rutile TiO2(110)-(1 × 1) surface with O2 exposure using Kelvin probe force microscopy. A drop in contact potential difference was observed at the steps, indicating that the work function locally decreased. Moreover, for the first time, we found that the drop in contact potential difference at a <1−11> step was larger than that at a <001> step. We propose a model for interpreting the surface potential at the steps by combining the upward dipole moment, in analogy to the Smoluchowski effect, and the local dipole moment of surface atoms. This local change in surface potential provides insight into the important role of the steps in the catalytic reaction.

Correlation between morphology and local mechanical and electrical properties of van der Waals heterostructures

2021 ◽  
Author(s):  
Borislav Vasic ◽  
Uros Ralevic ◽  
Sonja Aškrabić ◽  
Davor Čapeta ◽  
Marko Kralj
Keyword(s):  
Charge Transfer ◽  
Close Contact ◽  
Normal Load ◽  
Van Der Waals ◽  
Contact Potential Difference ◽  
Electrical Current ◽  
Potential Difference ◽  
Electrical Measurements ◽  
Contact Potential ◽  
Contact Mode

Abstract Properties of van der Waals (vdW) heterostructures strongly depend on the quality of the interface between two dimensional (2D) layers. Instead of having atomically flat, clean, and chemically inert interfaces without dangling bonds, top-down vdW heterostructures are associated with bubbles and intercalated layers (ILs) which trap contaminations appeared during fabrication process. We investigate their influence on local electrical and mechanical properties of MoS2/WS2 heterostructures using atomic force microscopy (AFM) based methods. It is demonstrated that domains containing bubbles and ILs are locally softer, with increased friction and energy dissipation. Since they prevent sharp interfaces and efficient charge transfer between 2D layers, electrical current and contact potential difference are strongly decreased. In order to reestablish a close contact between MoS2 and WS 2 layers, vdW heterostructures were locally flattened by scanning with AFM tip in contact mode or just locally pressed with an increased normal load. Subsequent electrical measurements reveal that the contact potential difference between two layers strongly increases due to enabled charge transfer, while local I/V curves exhibit increased conductivity without undesired potential barriers.

Contact Potential Difference as a Non-Destructive Testing of Steel

2021 ◽  
Vol 316 ◽  
pp. 258-263
Author(s):  
L.P. Aref'eva ◽  
A.G. Sukijazov ◽  
Yu.V. Dolgachev
Keyword(s):  
Chemical Composition ◽  
Contact Potential Difference ◽  
Electron Work Function ◽  
Sharp Decrease ◽  
Sample Surface ◽  
Probe Method ◽  
Potential Difference ◽  
Kelvin Probe ◽  
Contact Potential ◽  
Kelvin Probe Method

For steels of different grades, the effect of the chemical composition, structure, and surface etching on the contact potential difference is studied using the Kelvin probe method. It was shown experimentally that, with a change in the structure and chemical composition, the contact potential difference changes. Etching the surface of the steel with a 4% solution of nitric acid leads to a sharp decrease in the magnitude of the contact potential difference, which allows us to conclude that the value of the electron work function from the sample surface increases. The ability to control the composition and structure of the material by the Kelvin probe method is shown.

Conception of the Kelvin Method on the Basis of a Mechanic-Electrical Transformation

2018 ◽  
Vol 63 (3) ◽  
pp. 269
Author(s):  
Yu. S. Zharkikh ◽  
S. V. Lysochenko
Keyword(s):  
Mechanical Energy ◽  
Contact Potential Difference ◽  
Electrical Potential ◽  
Potential Difference ◽  
Atomic Scale ◽  
Measured Signal ◽  
Electrical Potential Difference ◽  
Kelvin Probe ◽  
Contact Potential ◽  
Electrostatic Charges

The Kelvin method was based on the concept of the dynamic capacitor recharging by a contact potential difference. The present paper draws attention to the fact that the contact potential difference is not the same physical agent as the electrical potential difference due to the electromotive force. It cannot act as an active electrical voltage and, accordingly, cause the flow of an electric recharging current. The real reason for the appearance of a measured signal is the transformation of the electrode movement mechanical energy into the electric current energy. The current is generated due to periodic changes in the screening conditions of electrostatic charges above the investigated surface. Investigations are made of the method sensitivity to the amount of charges on the sample surface. It is shown that the measurement results are interpreted without invoking the ideas of the work function. Therefore, the method can besuccessfully used in studies of organic and biological materials and electrolytes. The proposed mechanism is applicable in both the investigations of macroscopic distributions of the surfacecharge and the atomic scale in the Kelvin probe force microscopy.

scholarly journals Open-loop amplitude-modulation Kelvin probe force microscopy operated in single-pass PeakForce tapping mode

2021 ◽  
Vol 12 ◽  
pp. 1115-1126
Author(s):  
Gheorghe Stan ◽  
Pradeep Namboodiri
Keyword(s):  
Amplitude Modulation ◽  
Contact Potential Difference ◽  
Open Loop ◽  
Kelvin Probe Force Microscopy ◽  
Potential Difference ◽  
Kelvin Probe ◽  
Contact Potential ◽  
Force Microscopy ◽  
Single Pass ◽  
Afm Probe

The open-loop (OL) variant of Kelvin probe force microscopy (KPFM) provides access to the voltage response of the electrostatic interaction between a conductive atomic force microscopy (AFM) probe and the investigated sample. The measured response can be analyzed a posteriori, modeled, and interpreted to include various contributions from the probe geometry and imaged features of the sample. In contrast to this, the currently implemented closed-loop (CL) variants of KPFM, either amplitude-modulation (AM) or frequency-modulation (FM), solely report on their final product in terms of the tip–sample contact potential difference. In ambient atmosphere, both CL AM-KPFM and CL FM-KPFM work at their best during the lift part of a two-pass scanning mode to avoid the direct contact with the surface of the sample. In this work, a new OL AM-KPFM mode was implemented in the single-pass scan of the PeakForce Tapping (PFT) mode. The topographical and electrical components were combined in a single pass by applying the electrical modulation only in between the PFT tip–sample contacts, when the AFM probe separates from the sample. In this way, any contact and tunneling discharges are avoided and, yet, the location of the measured electrical tip–sample interaction is directly affixed to the topography rendered by the mechanical PFT modulation at each tap. Furthermore, because the detailed response of the cantilever to the bias stimulation was recorded, it was possible to analyze and separate an average contribution of the cantilever to the determined local contact potential difference between the AFM probe and the imaged sample. The removal of this unwanted contribution greatly improved the accuracy of the AM-KPFM measurements to the level of the FM-KPFM counterpart.

scholarly journals Local contact potential difference of molecular self-assemblies investigated by Kelvin probe force microscopy

2011 ◽  
Vol 99 (23) ◽  
pp. 233102 ◽  
Author(s):  
Evan J. Spadafora ◽  
Mathieu Linares ◽  
Wan Zaireen Nisa Yahya ◽  
Frédéric Lincker ◽  
Renaud Demadrille ◽  
...  
Keyword(s):  
Contact Potential Difference ◽  
Kelvin Probe Force Microscopy ◽  
Potential Difference ◽  
Kelvin Probe ◽  
Contact Potential ◽  
Force Microscopy ◽  
Local Contact
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