Indium tin oxide or ITO is a transparent conducting oxide and is composed of indium, tin, and oxygen in varying proportions. It offers a unique combination of transparency and conductive properties. The highly transparent and electrically conductive ITO coatings are applied to substrates such as glass. Based on the oxygen content, ITO can either be ceramic or an alloy. Indium, which belongs to the same group as aluminum is a technologically critical element. The thin films of ITO are extensively used in numerous electronic applications, such as mobile phone touch screens, televisions and LCD monitors, and other gadgets. You can easily deposit these thin films on glass, PET, and other substrates.
ITO coated glass is formed by spreading a thin and uniform Indium Tin Oxide layer over a glass substrate. The process of depositing the film should be carried out with precision. It should be carried out in entirely vacuum-enclosed conditions. You need to strike a compromise between the conductivity and transparency of the film. This is because increasing the film thickness also increases the concentration of charge carriers. While this increases the film’s conductivity, it simultaneously decreases its transparency.
ITO is a clear, conductive liquid/film and it is mostly used in research and development. An ITO glass has low sheet resistance and high transmittance properties. These glass plates are usually laser cut in square and rectangular shapes, or customized circular shapes. Based on coating resistivity, customers can also customize the coating thickness. Here are few important things you should know before you proceed to buy ITO glass.
1. Deposition Process
ITO is generally deposited via expensive and energy-intensive processes that deal with physical vapor deposition (PVD). The deposition of ITO coatings is either performed in a purely reactive sputter process from metallic In-Sn alloy targets or ceramic ITO targets by deploying a quasi-reactive process. The sputtering technique is performed inside a vacuum chamber with a large size ITO sputtering target. Sputtering results in the formation of brittle layers. An alternative method based on particle-based technique, also known as tape casting is also used for depositing. The ITO coating can be carried out in an entirely vacuumed condition by magnetron sputtering method at around 300 degrees C. On a single-sided coating, the coated surface is conductive, while the other surface is insulated.
2. Cleaning Of ITO Coated Glass
Oil, dust, and grease can settle on the surface of ITO glass from the environment. You can clean it by using high-quality lint-free cotton dipped in an isopropyl alcohol solvent. The surface energy of the substrate changes with time due to the contamination. Hence, you should not keep the cleaned substrate unused for more than 24 hours.
3. Electrical Properties
The ITO films’ electrical properties largely depend on the film combination and deposition techniques like applied sputtering power, oxygen flow, substrate deposition temperature, and more. ITO is transparent to visible light. It shows relatively high electrical conductivity and low electrical resistivity.
4. Optical Properties
Indium–tin–oxide (ITO) films deposited by sputtering and e-gun evaporation on transparent and opaque substrates have high optimal transmittance capability. It shows excellent optical transmittance from the visible to the near-infrared wavelength range. Optical transmission is a measure of what proportion of light is transmitted through a turbid medium.
5. Other Properties
ITO coated glass shows high electrical surface resistance homogeneity. Moreover, it also shows high transmission uniformity and excellent abrasion resistance. It also has exceptional coating adhesion capability and low microroughness. The ITO glass is an N-type semiconductor. The chemical formula of ITO is Sn: In2O3.
6. Passivation Layer
Between the ITO layer and borosilicate glass surface, there is a passivation layer of silicon dioxide (SiO2). It helps to increase the quality and longevity of ITO-coated glass plates. It improves the charge-separation and transfer processes across semiconductor interfaces. Moreover, it also protects active semiconductor surfaces from the peripheral areas. These layers have good adhesion and are usually chemically inert corrosion-resistant dielectrics. The thickness of silicon dioxide sandwiched between the ITO layer and the glass surface is 25 nm.
7. Use Of ITO Coated Glass
ITO coated glass substrates are commonly used as conductive substrates in different applications. It is widely used in organic/inorganic heterojunction solar cells, Schottky solar cells, CdTe solar cells, and other various thin-film solar cells. ITO-coated glass and plastic substrates are also useful for shielding and reducing EMI and RFI. It is used as a transparent semiconductor oxide electrode material because of its transparency and high conductivity. ITO coated glass has optimal transparency, lower electrical resistance, excellent electromagnetic shielding properties, and is a thermally/chemically stable product. It provides optimum conductivity in solar cells and other devices. It is also used in LED/OLED manufacturing, photovoltaic cells, camera technology, switchable/smart windows, and other technologies.
Since the ITO Glass Substrate shows low sheet resistance and high transmittance, it is used widely in different applications. You can customize the design and thickness of the coating to efficiently meet your end-use.