Analysis of STM images with pure and CO-functionalized tips: A first-principles and experimental study

Gustafsson, Alexander; Okabayashi, Norio; Peronio, Angelo; Giessibl, Franz J.; Paulsson, Magnus

doi:10.1103/physrevb.96.085415

Cited by 24 publications

(31 citation statements)

References 43 publications

(63 reference statements)

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“…Calculated STM contrast of a CO dimer A single CO molecule prefers to stand upright when adsorbed on a top site of a Cu(111) surface, i.e., the C-O bonding axis is perpendicular to the surface. Such an adsorbate exhibits a solid radially symmetric conductance dip when scanned by a pure Cu tip [9,25].…”

Section: Resultsmentioning

confidence: 99%

“…In our previous development [9,25] of calculating STM images from localized-orbital DFT, we used the Bardeen's approximation [11] for the real-space propagated wave functions in the vacuum region. The wave functions are calculated on an equidistant discrete lattice utilizing a simple nearest-neighbour finite difference (FD) scheme.…”

Section: Methodology a Transmission Coefficientmentioning

confidence: 99%

“…Upon using the Bardeen's approximation we introduce a separation surface [9,25], S, in vicinity of the middle of the vacuum gap (where the total DFT potential reaches its maximum) and set the potential away from this slice as the average of the potential at S. The wave functions from the substrate, ϕ s , and the tip, ϕ t , are then computed equivalently, but separately from each side of the vacuum region.…”

Section: Methodology a Transmission Coefficientmentioning

confidence: 99%

“…With atomic force microscoscopy (AFM), the interaction between tip and sample is characterized, which allows for examination of the tip-apex structure [5][6][7][8]. The tip-apex structure may strongly influence the tunneling process, both when making a quantitative comparison between experimental and theoretical STM images [9], and when investigating the inelastic tunneling signal from an adsorbate species [10].…”

Section: Introductionmentioning

confidence: 99%

“…Our previous work on this topic [9,25] concerns first-principles modeling based on Bardeen's approximation, using localized-basis DFT. The wave functions close to the atoms were calculated in a localized basis set using Green's function techniques, whereafter they were propagated into the vacuum region in real space by utilizing the total DFT potential.…”

Section: Introductionmentioning

confidence: 99%

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STM contrast of a CO dimer on a Cu(1 1 1) surface: a wave-function analysis

Gustafsson¹,

Paulsson²

2017

J. Phys.: Condens. Matter

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We present a method used to intuitively interpret the STM contrast by investigating individual wave functions originating from the substrate and tip side. We use localized basis orbital density functional theory, and propagate the wave functions into the vacuum region at a real-space grid, including averaging over the lateral reciprocal space. Optimization by means of the method of Lagrange multipliers is implemented to perform a unitary transformation of the wave functions in the middle of the vacuum region. The method enables (i) reduction of the number of contributing tip-substrate wave function combinations used in the corresponding transmission matrix, and (ii) to bundle up wave functions with similar symmetry in the lateral plane, so that (iii) an intuitive understanding of the STM contrast can be achieved. The theory is applied to a CO dimer adsorbed on a Cu(111) surface scanned by a single-atom Cu tip, whose STM image is discussed in detail by the outlined method.

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Section: Resultsmentioning

confidence: 99%

Section: Methodology a Transmission Coefficientmentioning

confidence: 99%

Section: Methodology a Transmission Coefficientmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

STM contrast of a CO dimer on a Cu(1 1 1) surface: a wave-function analysis

Gustafsson¹,

Paulsson²

2017

J. Phys.: Condens. Matter

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Unusual Temperature Dependence of Bandgap in 2D Inorganic Lead‐Halide Perovskite Nanoplatelets

Shang

et al. 2021

Advanced Science

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Understanding the origin of temperature-dependent bandgap in inorganic lead-halide perovskites is essential and important for their applications in photovoltaics and optoelectronics. Herein, it is found that the temperature dependence of bandgap in CsPbBr 3 perovskites is variable with material dimensionality. In contrast to the monotonous redshift ordinarily observed in bulk-like CsPbBr 3 nanocrystals (NCs), the bandgap of 2D CsPbBr 3 nanoplatelets (NPLs) exhibits an initial blueshift then redshift trend with decreasing temperature (290-10 K). The Bose-Einstein two-oscillator modeling manifests that the blueshift-redshift crossover of bandgap in the NPLs is attributed to the significantly larger weight of contribution from electron-optical phonon interaction to the bandgap renormalization in the NPLs than in the NCs. These new findings may gain deep insights into the origin of bandgap shift with temperature for both fundamentals and applications of perovskite semiconductor materials.

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Monolayer Borophene Formation on Cu(111) Surface Triggered by ⟨11¯0⟩$\langle {1\bar{1}0} \rangle $ Step Edge

Li,

Yang,

et al. 2023

Small

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Borophene, a promising material with potential applications in electronics, energy storage, and sensors, is successfully grown as a monolayer on Ag(111), Cu(111), and Au(111) surfaces using molecular beam epitaxy. The growth of two‐dimensional borophene on Ag(111) and Au(111) is proposed to occur via surface adsorption and boron segregation, respectively. However, the growth mode of borophene on Cu(111) remains unclear. To elucidate this, scanning tunneling microscopy in conjunction with theoretical calculations is used to study the phase transformation of boron nanostructures under post‐annealing treatments. Results show that by elevating the substrate temperature, boron nanostructures undergo an evolution from amorphous boron to striped‐phase borophene (η = 1/6) adhering to the Cu step edge, and finally to irregularly shaped β‐type borophene (η = 5/36) either on the substrate surface or embedded in the topmost Cu layer. dI/dV spectra recorded near the borophene/Cu lateral interfaces indicate that the striped‐phase borophene is a metastable phase, requiring more buckling and electron transfer to stabilize the crystal structure. These findings offer not only an in‐depth comprehension of the β‐type borophene formation on Cu(111), but also hold potential for enabling borophene synthesis on weakly‐binding semiconducting or insulating substrates with 1D active defects.

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Analysis of STM images with pure and CO-functionalized tips: A first-principles and experimental study

Cited by 24 publications

References 43 publications

STM contrast of a CO dimer on a Cu(1 1 1) surface: a wave-function analysis

STM contrast of a CO dimer on a Cu(1 1 1) surface: a wave-function analysis

Unusual Temperature Dependence of Bandgap in 2D Inorganic Lead‐Halide Perovskite Nanoplatelets

Monolayer Borophene Formation on Cu(111) Surface Triggered by ⟨11¯0⟩$\langle {1\bar{1}0} \rangle $ Step Edge

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