Indium Tin Oxide Thin Film Deposition by Magnetron Sputtering at Room Temperature for the Manufacturing of Efficient Transparent Heaters

Abstract

Indium tin oxide (ITO) thin films are widely used as transparent electrodes in electronic devices. Many of those electronic devices are heat sensitive, thus their manufacturing process steps should not exceed 100 °C. Manufacturing competitive high-quality ITO films at low temperature at industrial scale is still a challenge. Magnetron sputtering technology is the most suitable technology fulfilling those requirements. However, ITO layer properties and the reproducibility of the process are extremely sensitive to process parameters. Here, morphological, structural, electrical, and optical characterization of the ITO layers deposited at low temperature has been successfully correlated to magnetron sputtering process parameters. It has been demonstrated that the oxygen flow controls and influences layer properties. For oxygen flow between 3–4 sccm, high quality crystalline layers were obtained with excellent optoelectronic properties (resistivity <8 × 10−4 Ω·cm and visible transmittance >80%). The optimized conditions were applied to successfully manufacture transparent ITO heaters on large area glass and polymeric components. When a low supply voltage (8 V) was applied to transparent heaters (THs), de-icing of the surface was produced in less than 2 min, showing uniform thermal distribution. In addition, both THs (glass and polycarbonate) showed a great stability when exposed to saline solution.

The ZnO-In2O3 Oxide System as a Material for Low-Temperature Deposition of Transparent Electrodes

“…They also noticed a decrease in conductivity at same doping level. In our case, it should also be noted that the achieved conductivity value for the ZIO thin film composition with 5.0 mol% In 2 O 3 corresponds to one of the best among values declared for transparent electrodes formed on unheated substrates [36][37][38][39].…”

Impact of composition on microstructural, electrical and optical properties of ZnO thin films incorporation by In 2 O 3 for solar cells

“…During the past 30 to 40 years, the majority of research has paid attention to binary compounds such as those mentioned above because they possess wide direct bandgap which make them available for most optoelectronic applications 2 . ZnO is a TOC thin film, so it is favorite for use in solar cells, optoelectronics, flat panel displays, and gas sensors 3,4 . However, it is worth noting that the electrical properties of undoped ZnO are insufficient to meet the growing demand for fabricating high‐performance semiconductor devices 5 .…”

ZnO Electrodeposition Model for Morphology Control

“…ITO back contacts are the traditional option for (semi)transparent photovoltaic devices and have relevant advantages for the new semiconductors based on ZnO and solid-state polymers [10]. However, market drive toward low-cost photovoltaics is reducing the use of ITO as a transparent electrode, first due to the expensive vacuum sputtering process required for preparing these electrodes [11], together with the strategic availability of indium (only 16,000 tons in earth [12]). Therefore, new generation of commercial devices have reduced dramatically the use of ITO for cost effective polymer solar cells.…”

“…New (semi)transparent back-contacts are introducing ZnO as an option [13] but losing some efficiency on charge separation. However, an extremely thin ITO layer (also recovered from other solar cells) can be upgraded by controlled electrodeposition of ZnO in practical applications [11,14]. ZnO serves as polymer support, also enhancing the mobility of photoexcited electrons [14].…”