The Effect of Atomic Oxygen on the Formation of Indium Tin Oxide in Thin Films
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Indium Tin Oxide (ITO) is a transparent conducting oxide that is used in at paneldisplays and optoelectronics. Highly conductive and transparent ITO lms arenormally produced by heating the substrate to 300 C during deposition excluding plastics to be used as a substrate material. This thesis reports on an investigation whether or not dual ion beam sputtering can be used to create high quality ITO lms at room temperature. The e ect of exposing the sample to an atomic versusmolecular oxygen ux during deposition was investigated. The vacuum chamber ofthe Texas State dual ion beam sputtering system was refurbished resulting in a lowering of the base pressure from 3x106 torr to 1.3x107 torr. Thin ITO lms on glass and silicon substrates were 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 lms were characterized by ellipsometry and four point probe measurements. The lm thickness and the ITO's optical properties, i.e. refraction and extinction coe cient, were determined from the ellipsometry data for lms sputtered at di erent oxygen ow rates (1-5 sccm). This data was used to calculate the resistivity and absorption coe cient of the sputtered ITO. The resistivity of the samples sputtered with atomic oxygen were lower than the resistivity for the samples made with molecular oxygen, achieving a minimum value of 2.67x103 cm. This value is comparable to what has been obtained by others using ion beam sputtering. The gure of merit (FOM), i.e. = , was calculated from the measurement data. The largest value obtained for the FOM was 0.08 1 Films sputtered with atomic oxygen had a FOM which was systematically 1.2 to 5 times larger than lms sputtered with molecular oxygen. Part of the work described in this thesis was presented at the spring 2012 meeting of the Texas Section of the American Physical Society.