Automated reed-type Kelvin probe for work function and surface photovoltage studies

Kumar, C. Suresh; Subrahmanyam, A.; Majhi, J.

doi:10.1063/1.1146813

Cited by 21 publications

(9 citation statements)

References 14 publications

(8 reference statements)

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“…The Raman scattering spectroscopy studies have been carried out by using an Ar ion laser with a 488 nm excitation source of a power 25 mW (Jobin Yvon Model HR800UV). The electrical conductivity measurements have been carried out on the films using an electrometer (Keithley-614) in the two point probe technique in the temperature range 300 to 600 ± 5 K. The surface work function has been measured (with an accuracy of 0.01 eV) by a reed-type Kelvin probe [14].…”

Section: Methodsmentioning

confidence: 99%

Physical properties of silver oxide thin films by pulsed laser deposition: effect of oxygen pressure during growth

Raju

Kumar

Subrahmanyam³

2009

J. Phys. D: Appl. Phys.

109

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Silver oxide thin films have potential applications in ultra-high density optical non-volatile memories and in fluorescence imaging. In this paper, the physical properties of silver oxide thin films prepared at room temperature by the pulsed laser deposition (PLD) technique with varying oxygen pressure during growth are reported. The oxygen pressure in the growth chamber is varied between 9 and 50 Pa. The x-ray diffraction (XRD) analysis showed that all the films were polycrystalline. With increasing oxygen pressure in the growth chamber, it is observed that (i) the hexagonal Ag2O transforms to monoclinic AgO, (ii) the grain size in the film increases from 59 to 200 nm, (iii) the surface roughness of the film increases from 9 to 42 nm, (iv) the resistivity of the films increases from 1 to 4 × 104 Ω m, (v) the surface work function of the films increases from 5.47 to 5.61 eV and (vi) the optical band gap of AgO thin films decreases from 1.01 to 0.93 eV. Raman spectroscopy on AgO thin films shows low wave number peaks corresponding to the stretching vibration of Ag–O bonds. This study shows that single phase AgO thin films, a requirement for plasmonic devices, can be prepared at room temperature by the PLD technique with an oxygen pressure of 20 Pa.

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Section: Methodsmentioning

confidence: 99%

Physical properties of silver oxide thin films by pulsed laser deposition: effect of oxygen pressure during growth

Raju

Kumar

Subrahmanyam³

2009

J. Phys. D: Appl. Phys.

109

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“…The scan rate was kept at 10 mV s −1 . The surface work function of the films was calculated from the contact potential difference (CPD) measured using a Kelvin probe [11]. The PC activities of the samples were evaluated by measuring the changes in the optical absorbance of methylene blue (MB) solution (10 mg l −1 ) in the wavelength range 400-800 nm.…”

Section: Methodsmentioning

confidence: 99%

Results on the electrochromic and photocatalytic properties of vanadium doped tungsten oxide thin films prepared by reactive dc magnetron sputtering technique

Karuppasamy¹,

Subrahmanyam²

2008

J. Phys. D: Appl. Phys.

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In this investigation, vanadium doped tungsten oxide (V : WO3) thin films are prepared at room temperature by reactive dc magnetron sputtering employing a tungsten–vanadium ‘inlay’ target. In comparison with pure sputtered tungsten oxide thin films, 11% vanadium doping is observed to decrease the optical band gap, enhance the colour neutral property, decrease the coloration efficiency (from 121 to 13 cm2 C−1), increase the surface work function (4.68–4.83 eV) and significantly enhance the photocatalytic efficiency in WO3 thin films. These observations suggest that (i) vanadium creates defect levels that are responsible for optical band gap reduction, (ii) multivalent vanadium bonding with terminal oxygen in the WO3 lattice gives rise to localized covalent bonds and thus results in an increase in the work function, and (iii) a suitable work function of V : WO3 with ITO results in an enhancement of the photocatalytic activity. These results on electrochromic and photocatalytic properties of V : WO3 thin films show good promise in the low maintenance window application.

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“…The surface work function/contact potential difference ͑V CPD ͒ between the TiO 2 films and the stainless steel reference electrode ͑⌽ R = 4.81 eV͒ has been measured by an indigenously designed and fabricated reed-type Kelvin probe; 16 the accuracy of the measurement is within 0.001 eV. The surface morphology of the films has been evaluated by on atomic force microscope ͑Digital Instruments Nanoscope IV͒.…”

Section: Characterization Of Tio 2 Thin Filmsmentioning

confidence: 99%

Studies on the room temperature growth of nanoanatase phase TiO2 thin films by pulsed dc magnetron with oxygen as sputter gas

Karuppasamy

Subrahmanyam

2007

Journal of Applied Physics

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Electrical and optical properties of Nb-doped TiO 2 films deposited by dc magnetron sputtering using slightly reduced Nb-doped TiO 2 − x ceramic targets J. Vac. Sci. Technol. A 28, 851 (2010); 10.1116/1.3358153 Influence of substrate temperature on growth of nanocrystalline silicon carbide by reactive magnetron sputtering J. Appl. Phys. 98, 024313 (2005); 10.1063/1.1985975Influence of working gas pressure on structure and properties of WO 3 films reactively deposited by rf magnetron sputtering J.The anatase phase titanium dioxide ͑TiO 2 ͒ thin films were deposited at room temperature by pulsed dc magnetron sputtering using pure oxygen as sputter gas. The structural, optical, electrical, and electrochromic properties of the films have been studied as a function of oxygen pressure in the chamber. The x-ray diffraction results indicate that the films grown above 4.5ϫ 10 −2 mbar are nanocrystalline ͑grain size of 28-43 nm͒ with anatase phase. The films deposited at the chamber pressure of 7.2ϫ 10 −2 mbar are found to be highly crystalline with a direct optical band gap of 3.40 eV, refractive index of 2.54 ͑at = 400 nm͒, and work function of 4.77 eV ͑determined by the Kelvin probe measurements͒. From the optical emission spectra of the plasma and transport of ions in matter calculations, we find that the crystallization of TiO 2 at room temperature is due to the impingement of electrons and ions on the growing films. Particularly, the negative oxygen ions reflected from the target by "negative ion effects" and the enhanced density of TiO, TiO + , TiO 2 + , and O 2+ particles in the plasma are found to improve the crystallization even at a relatively low temperature. From an application point of view, the film grown at 7.2ϫ 10 −2 mbar was studied for its electrochromic properties by protonic intercalation. It showed good electrochromic behavior with an optical modulation of ϳ45%, coloration efficiency of 14.7 cm 2 C −1 , and switching time ͑t c ͒ of 50 s for a 2 ϫ 2 cm 2 device at = 633 nm.

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Automated reed-type Kelvin probe for work function and surface photovoltage studies

Cited by 21 publications

References 14 publications

Physical properties of silver oxide thin films by pulsed laser deposition: effect of oxygen pressure during growth

Physical properties of silver oxide thin films by pulsed laser deposition: effect of oxygen pressure during growth

Results on the electrochromic and photocatalytic properties of vanadium doped tungsten oxide thin films prepared by reactive dc magnetron sputtering technique

Studies on the room temperature growth of nanoanatase phase TiO2 thin films by pulsed dc magnetron with oxygen as sputter gas

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