Synchrotron radiation XAFS studies of transition metal oxide thin films prepared by reactive magnetron sputtering Juris Purāns Institute of Solid State Physics University of Latvia Internet: RSD2011 J.Purans – ISSP,LU

Transparent Conductive Oxides RSD2011 J.Purans – ISSP,LU

Transparent Conductive Oxides (TCO) From 1980 =>n-type TCOs, with good optical and electrical properties RSD2011 J.Purans – ISSP,LU

T. Minami, Semicond. Sci. Technol. 20(2005) S35-S44. Transparent Conductive Oxides RSD2011 J.Purans – ISSP,LU

Time variable (”chromogenic”) window coatings Photochromic Thermochromic Electrochromic Gasochromic UV irradiation Temperature Electric voltage or charge Reducing/oxidizing gas RSD2011 J.Purans – ISSP,LU

Operating the Electrochromic Element The ECE can be colored by applying negative potential (-2.4 < U < 0 V) to the working electrode (WE) for a time t < 5 sec. W 6+ O 3 +e - + H + => HW 5+ O 3 The ECE can be bleached by applying positive potential (0 < U < +1.5 V) to the working electrode (WE) for a time t < 5 sec. W 6+ O 3 +e - + H + <= HW 5+ O 3 RSD2011 J.Purans – ISSP,LU

Why zinc oxide ? Resource availability Low cost material Non-toxicity High thermal/chemical stability Electrical resistivity tailored [ Ωcm] High transmittance in the VIS-IR Lithography compatible ZnO RSD2011 J.Purans – ISSP,LU

Why Ga as dopant? RSD2011 J.Purans – ISSP,LU

Presently HF magnetron sputtering is the background of the technology, but it is underproductive and quite expensive in comparison with DC and MF magnetron sputtering RSD2011 J.Purans – ISSP,LU

XRD Results RT, Cu anode RSD2011 J.Purans – ISSP,LU

ZnO samples prepared in ISSP (EXAFS Lab.) morphology ZnO/Si produced by magnetron sputtering in argon followed by oxidation in air at 800ºC ZnO/Si produced by magnetron sputtering in Ar-O 2 APCVD ZnO/Si sample (image size: 890  660 µm) RSD2011 J.Purans – ISSP,LU

DC magnetron deposition of Zn-based TCO-s: process control by plasma optical emission spectroscopy R.Kalendarev, K.Vilnis, A.Ecis, M.Zubkins, A.Azens, J.Purans Institute of Solid State Physics, University of Latvia, Riga, Latvia The scope: the usefulness of plasma Optical Emission Spectroscopy (OES) for the sputtering process tuning has been investigated with the aim to ensure the process stability and reproducibility, and the quality of ZnO:Al films in terms of [minimized] electrical resistivity and [maximized] optical transmittance Optical emission spectrum upon sputtering of a ZnAl target in an atmosphere of Argon and Oxygen RSD2011 J.Purans – ISSP,LU

Selected Zinc, Argon and Oxygen optical emission line intensities during the process conditioning and film deposition RSD2011 J.Purans – ISSP,LU

Although the film resistivity data is not completely free from scattering [yet], the correlation between the values of the OES line intensities upon film deposition and the film properties confirms the usefulness of OES for the deposition process control of ZnO:Al films Resistivity for ZnO:Al films deposited at different Zinc and Oxygen optical emission line intensity ratios. RSD2011 J.Purans – ISSP,LU

Film resistivity as a function of Zinc optical emission line I Zn /IZnmax ratio. The IZn/IZnmax ratio range corresponds to the oxygen flow range after the maximum in Zinc line intensity RSD2011 J.Purans – ISSP,LU

Acknowledgements We are grateful to the Eiropas Reģionālās attīstības fonda aktivitātes „Atbalsts zinātnei un pētniecībai” 2010/0272/2DP/ /10/APIA/VIAA/088http://www1.cfi.lu.lv/teor/ERAF/ RSD2011 J.Purans – ISSP,LU