Optical Properties of Indium-Doped ZnO Films

Abstract

Indium-doped ZnO (IZO) films with low In content (<6 at. %) were fabricated by rf helicon magnetron sputtering. The uniformity of the composites was confirmed by elemental analysis. The formation of an In–Zn–O solid solution was verified using X-ray diffraction (XRD) patterns. A wide, high-transmittance region (400–2000 nm) and >80% transmittance in the window of fiber optics telecommunication (1.30–1.55 µm) were observed. The incorporation of indium enhances the optical transmission in the designated visible and infrared wavelengths. The optical band gap shows a slight blue-shift with increasing In doping which can be explained by the Burstein–Moss effect. The Urbach tail parameter E0 increases with increasing indium content, which coincides with the increase in the full width half maximum (FWHM) of (0002) planes in XRD patterns. A decline in crystal quality with In incorporation in IZO films is also confirmed from photoluminescence (PL) spectra.