Search results for "Force Microscopy"

Nanogoniometry with scanning force microscopy: a model study of CdTe thin films.

2007

In this paper scanning force microscopy is combined with simple but powerful data processing to determine quantitatively, on a sub-micrometer scale, the orientation of surface facets present on crystalline materials. A high-quality scanning force topography image is used to determine an angular histogram of the surface normal at each image point. In addition to the known method for the assignment of Miller indices to the facets appearing on the surface, a quantitative analysis is presented that allows the characterization of the relative population and morphological quality of each of these facets. Two different CdTe thin films are used as model systems to probe the capabilities of this met…

Strain relaxation, extended defects and doping effects in InxGa1-xN/GaN heterostructures investigated by surface photovoltage

2020

Abstract We have analysed electrical properties of extended defects and interfaces in fully strained and partially relaxed InxGa1-xN/GaN heterostructures by means of Kelvin probe force microscopy and surface photovoltage spectroscopy. The study highlights the role of indium incorporation and Si doping levels on the charge state of extended defects including threading dislocations, V defects and misfit dislocations. Surface potential maps reveal that these defects are associated with a different local work function and thus could remarkably alter electron-hole recombination mechanisms of InxGa1-xN/GaN layers locally. Surface photovoltage spectra clearly demonstrate the role of misfit disloca…

Diacetylene Linked Anthracene Oligomers Synthesized by One-Shot Homocoupling of Trimethylsilyl on Cu(111)

2018

On-surface chemical reaction has become a very powerful technique to conjugate small precursor molecules and several reactions have been proposed with the aim to fabricate functional nanostructures on surfaces. Here we present an unforeseen adsorption mode of 9,10-bis-((trimethylsilyl)ethynyl)anthracene on a Cu(111)surface and the resulting one-shot desilylative homocoupling of of the adsorbate by annealing at 400 K. With a combination of high-resolution atomic force microscopy and density functional theory calculations, we found that the triple bonds and silicon atoms of the monomer chemically interact with the copper surface. After the oligomerization, we discovered that the anthracene un…

Influence of the chemical dissolution of MnS inclusions on the composition of passive films and the local electrochemical behaviour of stainless stee…

2006

Abstract Immersion of stainless steel containing MnS inclusions in aqueous electrolytes leads to the chemical dissolution of these heterogeneities. Chemical dissolution of MnS inclusions in 1M NaCl, pH=3 was studied using in-situ AFM and the dissolution rate of MnS was estimated between 0.04 and 0.19 μm 3 /min. The local electrochemical measurements reveal that the chemical dissolution of MnS inclusions promotes pitting corrosion. Similary, chemical dissolution of MnS inclusions in IM NaClO 4 , pH=3 solution modified the surface close to the inclusions by the presence of FeSO 4 in the passive film.

Ambipolar MoS2 Transistors by Nanoscale Tailoring of Schottky Barrier Using Oxygen Plasma Functionalization

2017

One of the main challenges to exploit molybdenum disulfide (MoS2) potentialities for the next-generation complementary metal oxide semiconductor (CMOS) technology is the realization of p-type or ambipolar field-effect transistors (FETs). Hole transport in MoS2 FETs is typically hampered by the high Schottky barrier height (SBH) for holes at source/drain contacts, due to the Fermi level pinning close to the conduction band. In this work, we show that the SBH of multilayer MoS2 surface can be tailored at nanoscale using soft O-2 plasma treatments. The morphological, chemical, and electrical modifications of MoS2 surface under different plasma conditions were investigated by several microscopi…

Environmental chamber for an atomic force microscope.

2007

A commercial atomic force microscope (AFM), originally designed for operation in ambient conditions, was placed inside a compact aluminum chamber, which can be pumped down to high vacuum levels or filled with a desired gaseous atmosphere, including humidity, up to normal pressure. The design of this environmental AFM is such that minimal intrusion is made to the original setup, which can be restored easily. The performance inside the environmental chamber is similar to the original version.

Detection of defects buried in metallic samples by scanning microwave microscopy

2011

This paper reports the local detection of buried calibrated metal defects in metal samples by a new experimental technique, scanning microwave microscopy. This technique combines the electromagnetic measurement capabilities of a microwave vector network analyzer with the subnanometer-resolution capabilities of an atomic force microscope. The network analyzer authorizes the use of several frequencies in the range 1--6 GHz, allowing three-dimensional tomographical investigation, which is useful for the detection of bulk defects in metal materials.

2021

Gold-assisted mechanical exfoliation currently represents a promising method to separate ultralarge (centimeter scale) transition metal dichalcogenide (TMD) monolayers (1L) with excellent electronic and optical properties from the parent van der Waals (vdW) crystals. The strong interaction between Au and chalcogen atoms is key to achieving this nearly perfect 1L exfoliation yield. On the other hand, it may significantly affect the doping and strain of 1L TMDs in contact with Au. In this paper, we systematically investigated the morphology, strain, doping, and electrical properties of large area 1L MoS2 exfoliated on ultraflat Au films (0.16-0.21 nm roughness) and finally transferred to an i…

Surface properties of AlInGaN/GaN heterostructure

2016

Abstract Surface structural, electronic and electrical properties of the quaternary alloy AlInGaN/GaN heterostructures are investigated. Surface termination, atomic arrangement, electronic and electrical properties of the (0001) surface and (10–11) V-defect facets have been experimentally analyzed using various surface sensitive techniques including spectroscopy and microscopy. Moreover, the effect of sub-band gap (of the barrier layer) illumination on contact potential difference (VCPD) and the role of oxygen chemisorption have been studied.

On-surface covalent linking of organic building blocks on a bulk insulator.

2011

On-surface synthesis in ultrahigh vacuum provides a promising strategy for creating thermally and chemically stable molecular structures at surfaces. The two-dimensional confinement of the educts, the possibility of working at higher (or lower) temperatures in the absence of solvent, and the templating effect of the surface bear the potential of preparing compounds that cannot be obtained in solution. Moreover, covalently linked conjugated molecules allow for efficient electron transport and are, thus, particularly interesting for future molecular electronics applications. When having these applications in mind, electrically insulating substrates are mandatory to provide sufficient decoupli…