The Effect of Annealing on Nanothick Indium Tin Oxide Transparent Conductive Films for Touch Sensors

Abstract

This study aims to discuss the sheet resistance of ultrathin indium tin oxide (ITO) transparent conductive films during the postannealing treatment. The thickness of the ultrathin ITO films is 20 nm. They are prepared on B270 glass substrates at room temperature by a direct-current pulsed magnetron sputtering system. Ultrathin ITO films with high sheet resistance are commonly used for touch panel applications. As the annealing temperature is increased, the structure of the ultrathin ITO film changes from amorphous to polycrystalline. The crystalline of ultrathin ITO films becomes stronger with an increase of annealing temperature, which further leads to the effect of enhanced Hall mobility. A postannealing treatment in an atmosphere can enhance the optical transmittance owing to the filling of oxygen vacancies, but the sheet resistance rises sharply. However, a higher annealing temperature, above 250 ∘ C, results in a decrease in the sheet resistance of ultrathin ITO films, because more Sn ions become an effective dopant. An optimum sheet resistance of 336 Ω/sqr was obtained for ultrathin ITO films at 400 ∘ C with an average optical transmittance of 86.8% for touch sensor applications.

Fabrication of highly conductive graphene/ITO transparent bi-film through CVD and organic additives-free sol-gel techniques

“…Transparent conductive oxide (TCO) is one of the most important and extensively studied classes of advanced functional materials, with applications such as smart windows, flat panel displays, liquid crystal displays (LCD), organic light emitting diodes (OLED), solar cells, and touch screens 1 – 9 . Tin (Sn) doped indium oxide, also known as indium tin oxide (ITO), is still employed in TCO-based industry, and offers the best combination of high optical transmittance and low electrical resistance, which properties are sensitive to the synthesis methods 10 – 12 . The aqueous precursor sol-gel technique has recently become of interest compared with the other synthesis methods of ITO, such as rf and dc sputtering, spray pyrolysis, vacuum evaporation, and pulsed laser deposition, due to the simple and low synthesis cost for bulk-scale production, possibility to change the film microstructure, chemical stoichiometry, and easy introduction of a dopant 11 – 15 .…”

Transparent and Flexible Vibration Sensor Based on a Wheel-Shaped Hybrid Thin Membrane

“…The transmittance increased significantly as the post-annealing temperature increased up to 250 °C (blue and orange lines) and converged to a similar level at 300 °C (magenta line). According to many previous studies [ 21 , 22 ], the conductivity of ITO increases as the thermal annealing temperature increases because the structure of the ITO films is rearranged and helps the Sn ions become effective dopants [ 22 ]. In this work, the sheet resistance of the ITO layer, which was approximately 1473 Ω/□ in the as-deposited sample, decreased to 45.76 Ω/□ at 300 °C ( Figure 2 b).…”

“…When the annealing temperature reached 300 °C, the size of the crystal was found to be slightly small, at approximately 70 nm. As D increases, the grain-boundary scattering of visible light and electrons decreases and the carrier lifetime increases, which affects the transmittance and conductivity of ITO on the SU-8 layer [ 22 ]. Thus, the D values of the obtained ITO film can explain why the transparency and conductivity of ITO on SU-8 increased up to the thermal annealing temperature of 250 °C and why these properties did not increase at 300 °C.…”

Annealing Effect on (SnO<SUB>2</SUB>)<SUB>0.3</SUB>:(In<SUB>2</SUB>O<SUB>3</SUB>)<SUB>0.7</SUB><SUB> </SUB>Solar Cell Prepared by PLD Technique

“…Figure 4 shows the transmission spectra for In 2 O 3 :SnO 2 annealed at different temperature. It shows that the transmission increase with increasing annealing temperature reaching 85% in visible range, as a result of enhance the crystallinety [11].…”