Properties of indium tin oxide thin films grown by Ar ion beam sputter deposition

Abstract

Indium tin oxide (ITO) thin films were grown by Ar ion beam sputter deposition under systematic variation of ion energy, geometrical parameters, and O2 background pressure and characterized with regard to the film thickness, growth rate, crystalline structure, surface roughness, mass density, composition, electrical, and optical properties. The growth rate shows an over-cosine, forward-tilted angular distribution with a maximum, which increases with increasing ion energy, increasing ion incidence angle, and decreasing O2 background pressure. ITO films were found to be amorphous with a surface roughness of less than 1 nm. Mass density and composition show only small changes with increasing scattering angle. The electrical resistivity behavior in dependence on the process parameters is complex. It is not only driven by the O2 background pressure but also very much by the scattering angle. The observed behavior can be understood only if competing processes are considered: (i) reduction of the number of oxygen vacancies due to the presence of O2 background gas and (ii) defect generation and preferential sputtering of oxygen at the surface of the growing films due to the impact of high-energy scattered particles. Even though absolute numbers differ, optical characterization suggests a similar systematics.

High quality optical Indium Tin Oxide (ITO) layers deposited by ion beam sputtering (IBS)

“…This results in extremely smooth, dense and homogeneous layers in regard to the optical properties of the product. Whereas this advantage is well known and established for the standard oxide materials (SiO 2 , Ta 2 O 5 , Nb 2 O 5 , TiO 2 ), the behaviour of ITO as a sputtering material had been studied to a limited extent to our knowledge [5]. This study confirms the advantages of IBS on ITO as a sputtering material when electrical conductivity of the layers is additionally required.…”

Annealing-free fabrication of high-quality indium tin oxide films for free-carrier-based hybrid metal–semiconductor nanophotonics

“…The model was updated with the transmission intensity data to ensure a comprehensive analysis of the optical properties. To obtain the permittivity we use the general oscillator approach using a function consisting of three terms: (i) Drude, (ii) Tauc–Lorentz and (iii) Gaussian oscillators, typically used for this material 55 , 56 .…”