Work function change caused by alkali ion sputtering

Villegas, A.; Kudriavtsev, Yu.; Godines, A.; Asomoza, R.

doi:10.1016/s0169-4332(02)00706-7

Cited by 17 publications

(15 citation statements)

References 4 publications

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“…We believe that emitting surface (first two mono atomic layers) represents a ''mixture'' of oxygen atoms, forming 70-80% for the used oxygen pressure, silicon atoms and cesium atoms, implanted due to previous bombardment. Cesium surface concentration was estimated around 12-15% for cesium ion sputtering of Si with 15 keV primary ion energy [2]. The close cesium concentration we estimated for the oxygen flooding regime.…”

Section: Resultssupporting

confidence: 74%

“…In the limits of the estimated surface composition all found experimental data can be easy explained. Indeed, additionally to Cs-Si surface dipole [2], Cs-O dipoles appear on the surface, which have higher dipole moment in comparison with Cs-Si dipoles. The electric field, formed by these dipoles, increases, and, as a consequence, the corresponding work function change increases, too.…”

Section: Resultsmentioning

confidence: 99%

“…So, the WF of any Ar + ion bombarded surface should be equal to the WF of the polycrystalline target (whose value is known). The work function change was found equal to À2.45 eV, when we changed Ar + ions sputtering onto Cs + ion sputtering of silicon with primary ion energy of 15 keV [2].…”

Section: Methodsmentioning

confidence: 96%

“…Scheme of such measurements was described in details in our previous work [2]: energy of www.elsevier.com/locate/apsusc Available online at www.sciencedirect.com Applied Surface Science 254 (2008) 4961-4964 secondary ions, passing through the energy analyzer of the double focusing mass spectrometer (Cameca IMS-3f-7f), is a sum of their own energy and the accelerating potential, applied to the sample. So, any change of WF of emitted surface leads to a change on secondary ion energy, measured as a contact potential difference between the sample potential and the electrode potential of the energy analyzer.…”

Section: Methodsmentioning

confidence: 99%

“…That appears as a shift of experimental energy distribution curve. The relative WF change can be transferred into an absolute value using a ''reference'' analysis of the energy distribution performed under Ar + ion sputtering [2]. In the case of argon ion sputtering WF change happens due to a partial amorphization of a near surface layer.…”

Section: Methodsmentioning

confidence: 99%

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Cesium ion sputtering with oxygen flooding: Experimental SIMS study of work function change

Kudriatsev

Villegas

Gallardo-Hernández

et al. 2008

Applied Surface Science

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Section: Resultssupporting

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 96%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

Cesium ion sputtering with oxygen flooding: Experimental SIMS study of work function change

Kudriatsev

Villegas

Gallardo-Hernández

et al. 2008

Applied Surface Science

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Low work function thin film growth for high efficiency thermionic energy converter: Coupled Kelvin probe and photoemission study of potassium oxide

Morini

Dubois

Robillard

et al. 2014

Physica Status Solidi (a)

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Recent researches in thermal energy harvesting have revealed the remarkable efficiency of thermionic energy converters comprising very low work function electrodes. From room temperature and above, this kind of converter could supply low power devices such as autonomous sensor networks. In this type of thermoelectric converters, current injection is mainly governed by a mechanism of thermionic emission at the hot electrode which explains the interest for low work function coating materials. In particular, alkali metal oxides have been identified as excellent candidates for coating converter electrodes. This paper is devoted to the synthesis and characterization of potassium peroxide K2O2 onto silicon surfaces. To determine optimal synthesis conditions of K2O2, we present diagrams showing the different oxides as a function of temperature and oxygen pressure from which phase stability characteristics can be determined. From the experimental standpoint, we present results on the synthesis of potassium oxide under ultra high vacuum and controlled temperature. The resulting surface is characterized in situ by means of photoemission spectroscopy (PES) and contact potential difference (CPD) measurements. A work function of 1.35 eV is measured which and the expected efficiency of the corresponding converter is discussed. It is generally assumed that the decrease of the work function in the alkali/oxygen/silicon system, is attributed to the creation of a surface dipole resulting from a charge transfer between the alkali metal and oxygen.

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