Gold grown epitaxially on mica: conditions for large area flat faces

DeRose, James; Thundat, Thomas; Nagahara, Larry A.; Lindsay, Stuart

doi:10.1016/0039-6028(91)91204-b

Cited by 234 publications

(129 citation statements)

References 18 publications

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“…Epitaxial gold surfaces 120 nm thick were prepared by electron beam evaporation of gold onto freshly cleaved mica surfaces heated to a temperature of 4800C (29) and cut into 0.48-cm disks. Gold surfaces were chemically modified by immersing for 24 hr in 0.005 M aqueous solutions of either cystamine (Aldrich), which becomes 2-mercaptoethylamine on the surface, or 2-dimethylaminoethanethiol (Aldrich), rinsed thoroughly in water, and air dried.…”

Section: Methodsmentioning

confidence: 99%

Immobilization of DNA for scanning probe microscopy.

Allison

Bottomley

Thundat

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

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Reproducible scanning e microscope and atomic force microscope images of entire molecules of uncoated pasmid DNA chemically bound to surfaces are presented. The chemicaily mediated immobilization of DNA to surfaces and subsequent snning tunneling microscope imaging of DNA molecules demonstrate that the problem of molecular instability to forces exerted by the probe tip, inherent with nning probe microscopes, can be prevented. (12,13) surfaces. However, because topographic contrast is generally used to locate these extremely fine (2-nm diameters) molecules by scanning probe techniques, the DNA mounting substrate must be extremely flat. Surfaces with atomic flatness are ideal but usually lack sites that might anchor DNA either mechanically or chemically, thereby preventing displacement or removal by the scanning probe tip. Attempts to immobilize DNA on surfaces using electrochemical methods (14, 15) and covalent linking (13, 16, 17) of DNA to surfaces have been successful, but to date only images of DNA fragments have been reported. Evidence for improved surface binding came from examination ofa surface frequently imaged with the AFM. Mica, although atomically flat, is an insulator and therefore cannot be imaged with the STM but is well suited for the AFM. By simply drying a drop of a DNA-containing buffer solution onto freshly cleaved mica, one can routinely obtain AFM images of DNA strands within minutes (18-21), perhaps stabilized by hydrogen bonding of Si-OH to DNA. Recently a technique that replaced potassium ions in the mica surface with magnesium ions, promoting stronger binding of DNA to mica resulting in improved AFM images, has been described (22)(23)(24). Since the forces between the probe and the surface are roughly comparable in STM and AFM, the AFM work gave us hope that with a properly modified conducting surface to stabilize DNA, routine imaging of DNA by STM should be possible. Using an approach that allows a thiol group at one end of an organic molecule to bind to a gold surface (25) and a charged head group at the other end to attract and immobilize the polyanionic DNA for STM imaging (26) we present the STM images of entire plasmid molecules. METHODSPlasmid DNA (3204 base pairs, pBS+ from Stratagene) was extracted from Escherichia coli, concentrated by cesium chloride/ethidium bromide equilibrium centrifugation, ethanol precipitated, and resuspended in 10 mM Tris.HCl/0. 1 mM EDTA (TE) at pH 7.5 to a final concentration of 500 gg/ml (27). Circular DNA was relaxed by x-ray (70,000 rads; 1 rad = 0.01 Gy) mediated single-strand nicking of supercoiled molecules. Linearized plasmid was obtained by treatment with the restriction endonuclease Sma I. Agarose gel (0.8-1% agarose) electrophoresis was used to differentiate supercoiled from relaxed plasmid and linearized DNA (27). Relaxed plasmid DNA was radiolabeled by nick-translation in the following reaction mixture: 35 pl of DNA (500 Ag/ml), 5 pl (10x) of NT buffer (500 mM Tris-HCl, pH 7.5/50 mM MgCl2/100 mM 2-mercaptoethanol/1 mg of nuclease-...

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Section: Methodsmentioning

confidence: 99%

Immobilization of DNA for scanning probe microscopy.

Allison

Bottomley

Thundat

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

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“…The effect of different parameters such as deposition rate, thickness, pressure, substrate heating and film annealing on the morphology of the deposited gold film on different substrate materials, including silicon, mica and glass, has been investigated previously [12][13][14][15][16][17][18][19][20] . Studies showed that a deposition rate of less than 1 nm s -1 gives a smoother surface 14 , the chamber pressure (<10 -5 Torr) is insignificant compared to other factors 14,15 , the thickness of evaporated gold film has an effect on the size of the island, and [111] plateaus, with lateral dimensions in the range of 200 to 300 nm, occur for film thicknesses greater than 100 nm 17 . Moreover, studies reveal that the substrate temperature during deposition has a great influence on flatness and size of deposited gold grains 12,14,15,18,19 .…”

Section: Introductionmentioning

confidence: 99%

“…Studies showed that a deposition rate of less than 1 nm s -1 gives a smoother surface 14 , the chamber pressure (<10 -5 Torr) is insignificant compared to other factors 14,15 , the thickness of evaporated gold film has an effect on the size of the island, and [111] plateaus, with lateral dimensions in the range of 200 to 300 nm, occur for film thicknesses greater than 100 nm 17 . Moreover, studies reveal that the substrate temperature during deposition has a great influence on flatness and size of deposited gold grains 12,14,15,18,19 . By increasing the substrate temperature during deposition, adatoms and surface atoms are in a higher energy state compared to unheated substrate 18 .…”

Section: Introductionmentioning

confidence: 99%

Room temperature thermally evaporated thin Au film on Si suitable for application of thiol self-assembled monolayers in micro/nano-electro-mechanical-systems sensors

Mahmoodi

Rushdi

Bowen

et al. 2017

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Gold is a standard surface for attachment of thiol-based self-assembled monolayers (SAMs). To achieve uniform defect free SAM coatings, which are essential for bio/chemical sensing applications, the gold surface must have low roughness, and be highly orientated. These requirements are normally achieved by either heating during Au deposition or post deposition Au surface annealing. This paper shows that room temperature deposited gold, can afford equivalent gold surfaces, if the gold deposition parameters are carefully controlled. This observation is an important result as heating (or annealing) of the deposited gold can have a detrimental effect on the mechanical properties of the silicon on which the gold is deposited used in microsensors. The paper presents the investigation of the morphology and crystalline structure of Au film prepared by thermal evaporation at room temperature on silicon. The effect of gold deposition rate is studied, and it is shown that by increasing the deposition rate from 0.02 nm s -1 to 0.14 nm s -1 the gold surface RMS roughness decreases, whereas the grain size of the deposited gold is seen to follow a step function decreasing suddenly between 0.06 and 0.10 nm s -1 . The XRD intensity of the preferentially [111] orientated gold crystallites is also seen to increase as the deposition rate increases up to a deposition rate of 0.14 nm s -1 . Formation and characterization of 1-dodecanethiol on these Au coated samples is also studied using contact angle. It is shown that by increasing the Au deposition rate the contact angle hysteresis (CAH) decreases until it plateaus, for a deposition rate greater than 0.14 nm s -1 , where the CAH is smaller than 9 degrees which is an indication of homogeneous SAM formation, on a smooth surface. 2

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“…Due to the weak interlayer van der Waals force, atomically flat (001) surfaces can be created by exfoliation along the (001) plane, making it a suitable substrate for van der Waals epitaxy. 35 Moreover, muscovite is transparent and flexible when its thickness is in the micrometer range and with that muscovite is suitable for flexible and Published by AIP Publishing. 108, 253104-1 transparent electronics if integrated functional devices can be implemented on it.…”

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confidence: 99%

Van der Waals epitaxy of functional MoO2 film on mica for flexible electronics

Hao

Lin

Liu

et al. 2016

Applied Physics Letters

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Gold grown epitaxially on mica: conditions for large area flat faces

Cited by 234 publications

References 18 publications

Immobilization of DNA for scanning probe microscopy.

Immobilization of DNA for scanning probe microscopy.

Room temperature thermally evaporated thin Au film on Si suitable for application of thiol self-assembled monolayers in micro/nano-electro-mechanical-systems sensors

Van der Waals epitaxy of functional MoO2 film on mica for flexible electronics

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