Metal-Semiconductor Transition on the Surface and in the Bulk of Europium Hydride Thin Film

• Authors: M. Knor , R. Nowakowski , R. Duś
• Languages of publication: EN

Abstracts

EN

Thin europium films (20-50 nm thick) on a glass substrate were transformed into EuH_x (0 < x < 2) by interaction with H_2 introduced into the reactor in successive calibrated doses. By measuring the pressure, the hydrogen uptake (H/Eu) was determined at every step of the reaction. In situ monitoring of bulk properties (electrical resistance R(H/Eu), relative transparency to light T(H/Eu)/T_0 and (H/Eu) dependent light transparency spectrum) confirms metal-semiconductor transition at room temperature. Both the electrical resistance and optical transparency of the film strongly increase with hydrogen concentration as a consequence of the resulting increase of the content of semiconducting dihydride. Moreover, the course of work function changes ΔΦ(H/Eu) indicates inversion of the charge-transfer direction on the surface. The transition at room temperature from positively to negatively polarized hydrogen adsorbate was observed in situ during hydrogen uptake. As a result, the work function at equilibrium state varies with hydrogen content from +18 to -18 mV with respect to pure metal film, reflecting the change of "mirror potential" generated on the surface due to the accumulation of hydrogen adsorbates in the subsurface region.

Keywords

EN

67.63.Gh; 73.61.-r; 78.66.-w; 73.20.-r

Discipline

• 73.20.-r: Electron states at surfaces and interfaces
• 78.66.-w: Optical properties of specific thin films(for optical properties of low-dimensional, mesoscopic, and nanoscale materials, see 78.67.-n; for optical properties of surfaces, see 78.68.+m)
• 73.61.-r: Electrical properties of specific thin films(for optical properties of thin films, see 78.20.-e and 78.66.-w; for magnetic properties of thin films, see 75.70.-i)
• 67.63.Gh: Atomic hydrogen and isotopes

• Publisher: Institute of Physics, Polish Academy of Sciences
• Journal: Acta Physica Polonica A
• Year: 2012
• Volume: 122
• Issue: 4
• Pages: 698-703

Dates

published

2012-10

received

2012-04-17

(unknown)

2012-08-30

Contributors

author

M. Knor

• Institute of Physical Chemistry, Polish Academy of Sciences, M. Kasprzaka 44/52, 01-224 Warszawa, Poland

author

R. Nowakowski

• Institute of Physical Chemistry, Polish Academy of Sciences, M. Kasprzaka 44/52, 01-224 Warszawa, Poland

author

R. Duś

• Institute of Physical Chemistry, Polish Academy of Sciences, M. Kasprzaka 44/52, 01-224 Warszawa, Poland

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Identifiers

DOI

10.12693/APhysPolA.122.698