Reproducibility of scanning tunneling spectroscopy of Si(111)7 × 7 using a build-up tip

Tomitori, Masahiko; Sugata, Keiichi; Okuyama, Goro; Kimata, Hideki

doi:10.1016/0039-6028(95)01377-6

Cited by 35 publications

(17 citation statements)

References 18 publications

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“…It is interesting to note that similar results have been reported in the literature. 26,40 Since these 6. ͑Color online͒ STS measures of Au͑111͒ surface. ͑a͒ dI / dV spectrum of the Au͑111͒ reconstructed surface ͑solid black line͒ and asymmetrical T as fit ͑z = 6.1 Å and ⌽ = 4.5 eV͒.…”

Section: Application To Experimental Datamentioning

confidence: 98%

Recovery of local density of states using scanning tunneling spectroscopy

et al. 2009

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Scanning tunneling spectroscopy (STS) provides a unique method for the investigation of the local surfaceprojected electron density of states (DOS), mostly for its capability of reaching atomic resolution. Such information is contained in a nonobvious way in STS data, and a proper understanding of the overall features of the system (sample+tip) is mandatory in order to obtain quantitative information. Several approaches have been proposed in the literature to tackle this problem. A common feature of these methods is that they are mostly based on a one-dimensional 1D-WKB description of the tunneling current. We present a critical analysis and an extension of the methods so far proposed, with the main goal of applying the results to STS experimental data. This study has been conducted by modeling the tip-sample system within the frame of 1D-WKB theory, investigating key open issues, such as the estimation of required but usually experimentally unknown parameters such as the tip-sample distance and the role played by the presence of a nonconstant tip local DOS on STS data. This investigation allows us to ascertain strengths and weaknesses of the existing methods and leads to an optimized and improved strategy which we propose for the analysis of STS data. We tested our conclusions on STS measurements of the Si(111)-7x7 and Au(111) surfaces, acquired with W and Cr tips

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Section: Application To Experimental Datamentioning

confidence: 98%

Recovery of local density of states using scanning tunneling spectroscopy

et al. 2009

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“…Electrochemically etched single crystal tungsten wire oriented in the ͑111͒ direction facilitates the fabrication of atomically sharp tips after complicated thermal or thermal-field treatment for special applications in ultrahigh vacuum. [6][7][8][9][10] However, polycrystalline tungsten and platinum-iridium wires for scanning tunneling microscopy or nonmetallic materials like silicon, silicon dioxide, and silicon nitrite for scanning force microscopy or scanning near-field optical microscopy serve more customary as probes, although the surface cleanliness and the reproducibility of relevant properties of such tips are often rather poor. To improve the surface cleanliness of these probes ion sputtering procedures, 11 sometimes combined with a thermal treatment, 12 are subsequently applied.…”

Section: Introductionmentioning

confidence: 99%

Nanostructuring of tips for scanning probe microscopy by ion sputtering: Control of the apex ratio and the tip radius

Hoffrogge

Kopf

Reichelt

2001

Journal of Applied Physics

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Single crystal diamond tips for scanning probe microscopy Rev. Sci. Instrum. 81, 013703 (2010); 10.1063/1.3280182 Scanning probe microscopy investigation of nanostructured surfaces induced by swift heavy ionsIon etching under well-defined conditions represents a very powerful tool to fabricate tips in a controlled and reproducible manner for Scanning Probe Microscopy which possess clean, relatively smooth, and oxide-free surfaces. The possibilities and limitations of ion etching are demonstrated thoroughly for tungsten, which is of particular interest for scanning tunneling microscopy. Iterative computer simulations and experimental studies are provided. The simulation of the etching process at the atomic level is based on the Monte Carlo program ͑Transport of Ions in Matter͒, which provides reliable values for the key input parameters such as the sputtering yield Y (,E ion ) and the mean ion range in the material for ion energies between 1 and 6 keV. The simulation program starts with a large tip radius as a crude form and asymptotically approaches a ''final form'' of a very sharp tip in the course of ion etching. Our experimental results with argon ions in the energy range up to 6 keV and crude electrochemically etched polycrystalline tungsten wire agreed very reasonably with the simulated results. For example, the minimum tip radius obtained experimentally amounts to approximately 5 nm. This value corresponds closely to the ion range, which obviously sets a limit to the smallest achievable tip radius by the effect of transmission sputtering. By variation of the angle between the ion beam and the macroscopic tip, the tip angle can be controlled in the range between 12°and 35°.

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“…STM images were obtained at RT using chemically etched ͓111͔-oriented single crystal W tips. 20 Typical filled state STM images of Ge covered Si͑111͒-7 ϫ 7 surfaces deposited at 150°C under a low flux of ϳ0.005 ML/ min are shown in Fig. 1.…”

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confidence: 99%