Microfour-point probe for studying electronic transport through surface states

Petersen, Chris; Grey, François; Shiraki, Ichiro; Hasegawa, Shuji

doi:10.1063/1.1329871

Cited by 71 publications

(55 citation statements)

References 16 publications

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“…One application for such probes, which has not yet been explored is local measurement of surface state conductivity of clean surfaces in ultrahigh vacuum, where minimal influence of the contacts on the surface properties is highly desired. 24 …”

Section: Discussionmentioning

confidence: 99%

Microcantilever equipped with nanowire template electrodes for multiprobe measurement on fragile nanostructures

Lin

Bøggild

Hansen

2004

Journal of Applied Physics

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We present a technique for fabricating nanoelectrode extensions to microcantilevers for multiprobe electrical characterization. For electrical measurements of fragile samples, such as thin films and nanostructures, it is advantageous to combine a small contact force with a small contact area, which can be done by reducing the dimensions of the electrodes to nanoscale dimensions. Here we report a fabrication method of a nanoscale four-point probe utilizing silicon nanowires as templates for metal electrodes. Using nanomanipulation, we attach 200-300 nm wide silicon nanowires to microfabricated cantilevers. By subsequently covering these nanowires with a metallic coating, they are made conducting and at the same time fixed to the cantilevers. These silicon nanowire four-point probes were tested on 7 and 35 nm thick Au films as well as poorly adhering 16 nm thin Au nanowires deposited on a silicon surface through a nanofabricated shadow mask. It was found that the nanowire extensions dramatically reduce the damage of the studied samples, while nearly reproducing the resistivity measurements of the unmodified, but more destructive micro four-point probes.

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Section: Discussionmentioning

confidence: 99%

Microcantilever equipped with nanowire template electrodes for multiprobe measurement on fragile nanostructures

Lin

Bøggild

Hansen

2004

Journal of Applied Physics

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“…4, because of a possible Schottky barrier between the surface states and the underlying bulk states [19] or a possible pn-junction between the surface-space-charge layer and the interior bulk. But, this simple picture appears to be at least qualitatively true, as demonstrated in recent measurements [20][21][22][23]. Two types of such microscopic four-point probes are introduced in Section 4.…”

Section: Electrical Conduction At Semiconductor Surfacesmentioning

confidence: 99%

“…Rather it must be attributed to the surface-state band inherent in the ffiffi ffi 3 p Â ffiffi ffi 3 p -Ag superstructure [20]. Although the surface-state conductivity on this surface had been detected by macroscopic four-probe measurements as a carrier-doping effect into the surface-state band, as mentioned before, micro-four-point probes enabled the direct detection of the contribution of the surface-state conductance [20,22].…”

Section: Microscopic Four-point Probesmentioning

confidence: 99%

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Electronic transport at semiconductor surfaces––from point-contact transistor to micro-four-point probes

Hasegawa

Grey

2002

Surface Science

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The electrical properties of semiconductor surfaces have played a decisive role in one of the most important discoveries of the last century, transistors. In the 1940s, the concept of surface states--new electron energy levels characteristic of the surface atoms--was instrumental in the fabrication of the first point-contact transistors, and led to the successful fabrication of field-effect transistors. However, to this day, one property of semiconductor surface states remains poorly understood, both theoretically and experimentally. That is the conduction of electrons or holes directly through the surface states. Since these states are restricted to a region only a few atom layers thick at a crystal surface, any signal from them might be swamped by conduction through the underlying bulk semiconductor crystal, as well as greatly perturbed by steps and other defects at the surface. Yet recent results show that this type of conduction is measurable using new types of experimental probes, such as the multi-tip scanning tunnelling microscope and the micro-four-point probe. The resulting electronic transport properties are intriguing, and suggest that semiconductor surfaces should be considered in their own right as a new class of electronic nanomaterials because the surface states have their own characters different from the underlying bulk states. As microelectronic devices shrink even further, and surface-to-volume ratios increase, surfaces will play an increasingly important role. These new nanomaterials could be crucial in the design of electronic devices in the coming decades, and also could become a platform for studying the physics of a new family of low-dimensional electron systems on nanometre scales. Ó

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“…A four-tip scanning tunneling microscope ͑STM͒ 3 and a microscopic four-point probe ͑4PP͒ based on silicon cantilevers were reported. [4][5][6] The latter are fabricated by a bulkmicromachining process and have already been commercialized by Capres S/A. 7 The negative photoresist SU-8 is used for the fabrication of structures with high aspect ratio and has mechanical properties that allow it to be introduced as base material for an increasing number of micromechanical devices.…”

Section: Introductionmentioning

confidence: 99%

Microscopic four-point probe based on SU-8 cantilevers

Keller

Mouaziz

Boero

et al. 2005

Review of Scientific Instruments

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A microscopic four-point probe ͑4PP͒ for resistivity measurements on thin films was designed and fabricated using the negative photoresist SU-8 as base material. The device consists of four microscopic cantilevers, each of them supporting a probe tip at the extremity. The high flexibility of SU-8 ensures a stable electrical point contact between samples and probe tip with all four electrodes even on rough surfaces. With the presented surface micromachining process, 4PPs with a probe-to-probe spacing of 10-20 m were fabricated. Resistivity measurements on thin Au, Al, and Pt films were performed successfully. The measured sheet resistances differ by less than 5% from those obtained by a commercial macroscopic resistivity meter. Due to the low contact forces ͑F cont Ͻ 10 −4 N͒, the 4PP is suitable to be applied also to fragile materials such as conducting polymers. Here the authors demonstrate the possibility of performing resistivity measurements on 100-nm-thick pentacene ͑C 22 H 14 ͒ films with a sheet resistance R s Ͼ 10 6 ⍀ / ᮀ.

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Microfour-point probe for studying electronic transport through surface states

Cited by 71 publications

References 16 publications

Microcantilever equipped with nanowire template electrodes for multiprobe measurement on fragile nanostructures

Microcantilever equipped with nanowire template electrodes for multiprobe measurement on fragile nanostructures

Electronic transport at semiconductor surfaces––from point-contact transistor to micro-four-point probes

Microscopic four-point probe based on SU-8 cantilevers

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