Optical, structural, and electrical properties of modified indium-tin-oxide (ITO) films on glass surface by low energy ion implantation

Indium-tin-oxide (ITO) is a degenerate, wide bandgap semiconductor, and is very useful as transparent electrode for flat panel display devices, solar cells, sensors, and organic light emitting diodes (OLED) because of its high optical transmittance and low resistivity. In this article, the optical, structural, and electrical properties of ITO thin films on glass surface are modified with 1 keV Ar+ ion implantation by varying ion doses and energies in the range 0.5–2.5 keV, at constant ion dose of 2 min. The optical transmission is improved with increasing ion doses and is enhanced up to 90% and 92% for larger ion doses at the wavelength 380 nm and 610 nm, respectively. The optical bandgap of ion implanted ITO films could be tailored in terms of ion doses and ion energies. The structural properties as investigated by X-ray diffraction (XRD) patterns indicate the modification of average crystalline size, which increases the average dislocation and strain in the lattice. The ion beam sputters the elements (Sn, In) in ITO films and decreases the Sn and In concentration as confirmed by X-ray photoelectron spectroscopy (XPS) study. The electrical properties of ion implanted ITO films could be tuned in terms of resistivity, mobility, and carrier concentration. The decrease of Sn concentration in ITO films is mainly responsible for the modification of electrical properties. The theoretical simulation of ion induced damage in ITO films using TRIM is employed to support experimental observations. The potential application of modified ITO films on optoelectronic devices is also suggested.