Enhanced optical and electrical properties of ITO on a PET substrate by hydrogen plasma and HCl treatment

This study examined the optical and electrical properties of indium tin oxide (ITO) films treated with a hydrogen plasma and a post-HCl solution. ITO films, 200 nm in thickness, were deposited on polyethylene terephthalate (PET) substrates by the radio frequency magnetron sputtering method. The samples were then exposed to an inductively coupled hydrogen plasma and this was followed by HCl:DI solution treatment. The work function of the ITO surface was decreased from 4.94 to 4.61 eV without thermal annealing. The sheet resistance was decreased due to the formation of a high density of O-H bonds and oxygen vacancies. Although the transmittance of the hydrogen-plasma-treated sample was decreased drastically by the formation of In/Sn clusters, enhanced transmittance and increased optical band gap without a deterioration of the electrical properties could be achieved effectively by removing the In/Sn clusters using a HCl solution.