Low cost PC based scanning Kelvin probe

Baikie, Iain D.; Estrup, P. J.

doi:10.1063/1.1149197

Cited by 149 publications

(84 citation statements)

References 30 publications

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“…Surface potential measurements, obtained using the Kelvin method [5], can determine the net charge as a function of position that resides in thin dielectric films after VUV irradiation. Once the surface potential is known, an estimate can be made for the VUV-induced charge density using the expression,…”

mentioning

confidence: 99%

Surface potential measurements of vacuum ultraviolet irradiated Al/sub 2/O/sub 3/, Si/sub 3/N/sub 4/, and SiO/sub 2/

Lauer

Shohet

2005

IEEE Trans. Plasma Sci.

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Abstract-Vacuum ultraviolet radiation (VUV), generated during plasma processing of semiconductors devices can induce charge on dielectric materials. By exposing dielectric coated wafers to synchrotron radiation of varying energy, it is possible to separate the photoemission and photoconductive effects, both of which result in an increase in the surface potential of the dielectric. Maps of the surface potential induced on the dielectrics by VUV can be obtained by the use of a Kelvin probe.Index Terms-Plasma damage, plasma radiation, vacuum ultraviolet radiation (VUV). DURING plasma processing, charging of dielectrics plays a leading role within the damage mechanisms of semiconductor devices and plasma-processed materials in general. This damage mechanism is greatly influenced by the plasma-emitted vacuum ultraviolet (VUV) radiation. VUV radiation with energies in the range of 7-21 eV can induce charge on dielectric materials. The radiation is absorbed in the exposed dielectric and it results in the generation of electron-hole pairs. Electrons that have enough energy to escape the dielectric layer can then be photoemitted, leaving the positively charged holes in the dielectric. However, this can only occur when the dielectric is exposed to a flux of photons with an energy above its threshold for photoemission. When enough electrons are photoemitted, the dielectric will develop a positive surface-charge layer. As the dielectric surface charges so that fewer and fewer electrons are being photoemitted, the incident photons will generate electron-hole pairs that remain in the dielectric. This can only occur if these photons have an energy larger than the bandgap of the dielectric. Photons with wavelengths that are strongly absorbed by the dielectric cause the generation of electron-hole pairs only in a very thin surface layer and produces what is in effect a surface conductivity. On the other hand, radiation with wavelengths that are weakly absorbed by the dielectric causes the generation of carriers throughout the bulk of the dielectric and thus creates a volume conductivity. Under these conditions, free electrons in the conduction band and free holes in the valence band that escape initial recombination can travel under the action of an electric field toward the boundaries of the dielectric, resulting in charge separation. Charge separation causes the dielectric to Manuscript

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confidence: 99%

Surface potential measurements of vacuum ultraviolet irradiated Al/sub 2/O/sub 3/, Si/sub 3/N/sub 4/, and SiO/sub 2/

Lauer

Shohet

2005

IEEE Trans. Plasma Sci.

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“…Such techniques have been applied in different research fields to characterize the electrical properties of materials on nanoscopic length scales. Scanning capacitance microscopy [5,6,7] and scanning kelvin probe microscopy [8,9] have been applied to semiconductors and semiconductor devices. The electrical properties of nanostructured materials adsorbed on insulating substrates, e.g.…”

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confidence: 99%

Probing ion transport at the nanoscale: Time-domain electrostatic force spectroscopy on glassy electrolytes

Schirmeisen

Taskiran

Fuchs

et al. 2004

Applied Physics Letters

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We have carried out time-domain electrostatic force spectroscopy on two different ion conducting glasses using an atomic force microscope. We compare the electrostatic force spectroscopic data obtained at different temperatures with macroscopic electrical data of the glasses. The overall consistency of the data shows that electrostatic force spectroscopy is capable of probing the ion dynamics and transport in nanoscopic subvolumes of the samples.Ion conducting crystals, glasses and polymers are widely used as solid electrolytes in batteries, fuel cells, and chemical sensors. A lot of research work is being carried out in order to find new materials with improved ionic conductivities. One method that is becoming more and more technologically relevant is nanostructuring of materials. It has, for instance, been found that the ionic conductivity of nanocrystalline ionic conductors can be increased by adding nanocrystalline insulators [1]. In the case of glasses, a conductivity enhancement can be achieved by the formation of nanocrystallites during partial crystallisation [2]. Furthermore, the ionic conductivity of polymer electrolytes can be improved considerably by incorporating nanoparticles, such as Al 2 O 3 , TiO 2 and ZrO 2 , into the polymer matrix [3].Up to now, there is no general agreement about the origin of these conductivity enhancement effects. A limiting factor hindering a better theoretical understanding and thus a more systematic preparation of improved materials is the traditional characterization of the ion dynamics by means of macroscopic techniques, such as conductivity spectroscopy, tracer diffusion measurements, and NMR relaxation techniques. In nanostructured solid electrolytes, diffusion pathways in different phases and at interfaces are believed to play an important role for the ion transport [1,4]. Therefore, an experimental method capable of probing ion transport on nanometer length scales would be highly desirable.In principle, electrostatic force microscopy and spectroscopy techniques using an atomic force microscope (AFM) are well suited for this purpose. Such techniques have been applied in different research fields to characterize the electrical properties of materials on nanoscopic length scales. Scanning capacitance microscopy [5,6,7] and scanning kelvin probe microscopy [8,9] have been applied to semiconductors and semiconductor devices. The electrical properties of nanostructured materials adsorbed on insulating substrates, e.g. carbon nanotubes and DNA molecules adsorbed on silica, have been studied by using electrostatic force microscopy techniques [10,11]. Israeloff and coworkers used timedomain electrostatic force spectroscopy in order to characterize dielectric fluctuations in thin polymer films at the glass transition [12,13,14].In this letter, we report, for the first time, on the application of electrostatic force spectroscopy for studying ion transport in solid electrolytes. To do this, we chose two ion conducting glasses with well-known macroscopic electrical properties....

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“…This can allow universal tuning of the workfunction by for example up to 1.3 eV by deposition of ultrathin polymer films on a variety of surfaces. 8 The workfunction of AZO herein was measured herein using a Kelvin probe (KP) 9 This instrument measures the workfunction difference (or contact potential, V C ) by bringing a vibrating probe tip in close proximity to the sample being measured (tungsten is used as an example in Figure 1). The instrument uses a current amplifier to measure the charging current (signal) as the distance between tip and the sample oscillates.…”

Section: Introductionmentioning

confidence: 99%

Workfunction of Al-Doped ZnO Films Deposited by Atomic Layer Deposition

Gordon

Bačić²,

Lopinski³

et al. 2018

Preprint

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Al-doped ZnO (AZO) is a promising earth-abundant alternative to Sn-doped In 2 O 3 (ITO) as an n-type transparent conductor for electronic and photovoltaic devices; AZO is also more straightforward to deposit by atomic layer deposition (ALD). The workfunction of this material is particularly important for the design of optoelectronic devices. We have deposited AZO films with resistivities as low as 1.1 × 10 −3 Ω cm by ALD using the industry-standard precursors trimethylaluminum (TMA), diethylzinc (DEZ), and water at 200 • C. These films were transparent and their elemental compositions showed reasonable agreement with the pulse program ratios. The workfunction of these films was measured using a scanning Kelvin Probe (sKP) to investigate the role of aluminum concentration. In addition, the workfunction of AZO films prepared by two different ALD recipes were compared: a "surface" recipe wherein the TMA was pulsed at the top of each repeating AZO stack, and a interlamellar recipe where the TMA pulse was introduced halfway through the stack. As aluminum doping increases, the surface recipe produces films with a consistently higher workfunction as compared to the interlamellar recipe. The resistivity of the surface recipe films show a minimum at a 1:16 Al:Zn atomic ratio and using an interlamellar recipe, minimum resistivity was seen at 1:19. The film thicknesses were characterized by ellipsometry, chemical composition by EDX, and resistivity by four-point probe.

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Low cost PC based scanning Kelvin probe

Cited by 149 publications

References 30 publications

Surface potential measurements of vacuum ultraviolet irradiated Al/sub 2/O/sub 3/, Si/sub 3/N/sub 4/, and SiO/sub 2/

Surface potential measurements of vacuum ultraviolet irradiated Al/sub 2/O/sub 3/, Si/sub 3/N/sub 4/, and SiO/sub 2/

Probing ion transport at the nanoscale: Time-domain electrostatic force spectroscopy on glassy electrolytes

Workfunction of Al-Doped ZnO Films Deposited by Atomic Layer Deposition

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