Fabrication and characterization of microtips for in situ scanning tunneling microscopy

Gewirth, Andrew A.; Craston, Derek H.; Bard, Allen J.

doi:10.1016/0022-0728(89)85018-1

Cited by 92 publications

(56 citation statements)

References 10 publications

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“…For most SECM studies, the ratio of the diameter of the entire tip end (electrode plus surrounding insulator, 2r s ) to that of the electrode itself, 2a, RG r s /a is typically around 10. Metal electrodes down to the nanometre scale can also be fabricated by sealing an etched Pt or Pt±Ir wire in a suitable insulating material, leaving just the etched end exposed [34,35]. If the SECM measurement involves simple non-invasive detection, then potentiometry, as well as amperometry, becomes a possibility, greatly extending the range of species and processes that can be investigated [36].…”

Section: Probesmentioning

confidence: 99%

Scanning electrochemical microscopy: beyond the solid/liquid interface

Barker

Gonsalves

Macpherson

et al. 1999

Analytica Chimica Acta

145

107

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Section: Probesmentioning

confidence: 99%

Scanning electrochemical microscopy: beyond the solid/liquid interface

Barker

Gonsalves

Macpherson

et al. 1999

Analytica Chimica Acta

145

107

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“…Tips were prepared from Pt/Ir ͑70%/30%͒ wires and then coated with epoxy leaving the end exposed. 12 Images were taken in constant current mode with 1.5 V tip bias (V b ) and approximately 15 pA set-point tunneling current (I t ).…”

mentioning

confidence: 99%

Placement of conjugated oligomers in an alkanethiol matrix by scanned probe microscope lithography

Chen

Reed

Asplund

et al. 1999

Applied Physics Letters

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We report the in situ replacement of conjugated molecules in an insulating matrix by scanned probe microscope lithography. High yield, programmable patterning of a self-assembled monolayer of dodecanethiol was performed by applying voltage pulses from a scanning tunneling microscope. Conjugated oligomers were observed to be subsequently chemisorbed onto the patterned sites. © 1999 American Institute of Physics. ͓S0003-6951͑99͒01031-1͔Scanned probe microscopy offers a method for manipulating and modifying materials at the atomic level. 1-3 Preliminary work has been done utilizing self-assembled monolayers ͑SAMs͒ as a substrate. [4][5][6][7][8][9] In this letter, we demonstrate reproducible in situ scanning tunneling microscope ͑STM͒ lithographic SAM patterning and subsequent replacement of conjugated molecules in an insulating matrix at selectively patterned locations. A schematic of the process is shown in Fig. 1.The initial substrate is a gold surface with an adsorbed SAM. An annealed Au/Cr ͑250 nm/50 nm͒ film on glass exhibited a Au͑111͒ surface with terraces of up to several hundred nanometers with herringbone reconstruction. 10 A dodecanethiol SAM was deposited from solution at room temperature. 11 Subsequent mounting in a Teflon liquid cell of an ambient STM chamber allowed for immersion in 1,4-dioxane ͑Aldrich͒ solvent for the replacement experiments.A Park Scientific ͓Universal SA1͔ tube-scanning ambient STM was used for both imaging and lithographic patterning. Tips were prepared from Pt/Ir ͑70%/30%͒ wires and then coated with epoxy leaving the end exposed. 12 Images were taken in constant current mode with 1.5 V tip bias (V b ) and approximately 15 pA set-point tunneling current (I t ).To perform lithography, we applied square voltage pulses to the SAM substrate with pulse amplitude (V p ) varying from 1.8 to 3.6 V and pulse duration (T p ) from 0.5 s to 0.5 s. A constant dc bias voltage (V b ) of 0.1 V was kept on the STM tip during the voltage pulses. A larger time constant ͑relative to the pulse width͒ in the feedback electronics is used to both maintain the tip at a constant height and avoid tip crashing. Figure 2 is an image of a sample after three consecutive voltage pulses with V p of 3.0 V and T p of 0.5 s. The tip was biased at V b of 0.1 V with I t of 0.5 nA. To have a better view of the profile of the patterned structures ͑pits͒, we invert the image by plotting the depth of the pits as positive z. The diameters and depths of the patterned structures are approximately 10 and 1.4 nm, respectively. The pit depth is the length of dodecanethiol SAM to within the measurement resolution of the STM system. A lithographic positioning program was used to move the tip to obtain these distinct, spatially separated patterns.We have studied the patterning yield of this STM lithography as a function of pulse voltage and pulse width ͑Fig. 3͒. The yield was defined as the percent of successful patterned structures ͑out of 50 pulses͒. Under appropriate pulse conditions patterns were produced with over 90% yiel...

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“…Insulated tips are prepared from conventional tips by covering with different insulation such as glass capillaries [1,18,19], fingernail polish [20], epoxy coverage [21,22], varnishes [23] and apiezon wax coverage [5,24]. The last one is often employed, because the grease is easy to use and is found to be inert in most electrolytes.…”

Section: In Situ Scanning Tunneling Microscopy Featuresmentioning

confidence: 99%

Surface Investigation by Scanning Tunnelling Microscopy in Liquid Medium

et al. 1993

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Scanning tunneling microscopy in liquid environment has gained an increased interest in recent years. The specific features of the in situ observation of surface structures at the solid/liquid interface are first presented. Next, a high resolution imaging of high oriented pyrolytic graphite (HOPG) graphite surface shows the potentiality of our home-made microscope. The 1ast study, performed on technological InP. substrates, illustrates the extensive applications of in situ imaging in the fields of semiconductor technology.

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Fabrication and characterization of microtips for in situ scanning tunneling microscopy

Cited by 92 publications

References 10 publications

Scanning electrochemical microscopy: beyond the solid/liquid interface

Scanning electrochemical microscopy: beyond the solid/liquid interface

Placement of conjugated oligomers in an alkanethiol matrix by scanned probe microscope lithography

Surface Investigation by Scanning Tunnelling Microscopy in Liquid Medium

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