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Nelson Simpson
Texas State University at San Marcos, Department of Physics, RFM 3228, 601 University Drive, San Marcos, TX78666.
Nelson Simpson
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Indium Tin Oxide (ITO) is a transparent conducting oxide that is used in flat panel displays and optoelectronics. Highly conductive and transparent ITO films are normally produced by heating the substrate to 300 degrees Celsius during deposition excluding plastics to be used as a substrate material. We are investigation whether or not dual ion beam sputtering can be used to create high quality ITO films at room temperature. The effect of exposing the sample to an atomic versus molecular oxygen flux during deposition is investigated. The vacuum chamber of the Texas State dual ion beam sputtering system is being refurbished to realize lower base pressures (from 3x10E-6 torr to 1.3x10E-7 torr). Thin ITO films on glass and silicon substrates are made by reactive dual ion beam sputtering using an atomic oxygen assist beam and a molecular oxygen assist beam. The optical and electrical properties of the deposited films are characterized by ellipsometry and four point probe measurements. The film thickness and the ITO's optical properties, i.e. refraction and extinction coeficient, are determined from the
ellipsometry data for films sputtered at different oxygen flow rates (1-5 sccm). This data is used to calculate the resistivity and absorption coefficient of the sputtered ITO. The resistivity of the samples sputtered with atomic oxygen seems to be lower than the resistivity for the samples made with molecular oxygen, achieving a minimum value of 2.67E-3 Ohm cm. This value is comparable to what has been obtained by others using ion beam sputtering. The figure of merit (FOM), i.e. the ratio of the resistivity and optical absorption, is calculated from the measurement data. The largest value obtained for the FOM is 0.08 reciprocal Ohms. Films sputtered with atomic oxygen have a FOM which, depending on the oxygen flow rate, is approximtely 1.2 to 5 times larger than films sputtered with molecular oxygen.
Publications and Presentations:
[1] Nelson Simpson, Wilhelmus Geerts, Anup Bandyopadhyay, "Optical Properties of Dual Ion Beam Sputtered Indium Tin Oxide Films on Glass and Silicon", oral presentation APS spring meeting of the Texas Section of the American Physical Society, March 22-24, 2012, San Angelo, Texas.
[2] Wilhelmus Geerts, Nelson Simpson, Alan Woodall, Maclyn Stuart Compton, Indium Tin Oxide Thin Films Deposited at Low Temperature using Dual Ion Beam Sputtering, MRS spring meeting, 2014, april 21-24.
[3] Maclyn Stuart Compton, Nelson Simpson, Elizabeth Leblanc, Michael A. Robinson, Wilhelmus J. Geerts, Electrical Properties of Permalloy Oxide grown by Dual Ion Beam sputtering, MRS spring meeting, 2014, april 21-24.
[4] Maclyn Compton, Elizabeth LeBlanc, Wilhelmus Geerts, Nelson Simpson, Michael Robinson, The Electric, Magnetic, and Optical Characteriation of Permalloy Oxide grown by Dual-Ion Beam Sputtering, 2014-APS March meeting, Denver.
[5] Wilhelmus Geerts, Nelson Simpson, Alan Woodall, Maclyn Compton, The Influence of Atomic Oxygen on the figure of merit of Indium Tin Oxide thin Films grown by reactive Dual Ion Beam Sputtering, 2014-Aps March meeting, Denver.
[6] Nelson Simpson, The effect of atomic oxygen on the formation of indium tin oxide thin films, thesis Texas State University, San Marcos, Spring 2013 (thesis).
[7] Maclyn Stuart Compton, Nelson A. Simpson, Elizabeth G. LeBlanc, Michael A. Robinson, Wilhelmus J. Geerts, "Electrical and Optical Properties of Permalloy Oxide grown by dual ion beam sputtering", oral presentation 2014 MRS Spring meeting, San Francisco, California.
[8] Wilhelmus J. Geerts, Nelson Simpson, Maclyn S. Compton, Alan Woodall, Indium Tin Oxide thin films deposited at low temperature using Dual Ion Beam Sputtering, poster presentation 2014 MRS Spring meeting, San Francisco, California.
[9] Maclyn Stuart Compton, Nelson A. Simpson, Elizabeth G. LeBlanc, Michael A. Robinson, Wilhelmus J. Geerts, Electrical and Optical Properties of Permalloy Oxide grown by dual ion beam sputtering, 6 page paper published in Mat. Res. Soc. Symp. 1708 (2014) mrss 14-1708-VV08-01.
[10] Wilhelmus J. Geerts, Nelson Simpson, Maclyn S. Compton, Alan Woodall, Indium Tin Oxide thin films deposited at low temperature using Dual Ion Beam Sputtering, 6 page paper published in Mat. Res. Soc. Symp. 1699 (2014) mrss14-1699-ll05-28.
Nelson graduated from Texas State in May 2013 and is working for Ford AV
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