Properties of Indium-Doped ZnO Films Prepared in an Oxygen-Rich Plasma

Abstract

Indium-doped zinc oxide (ZnO:In) films were prepared in an Ar:O 2 plasma by reactive magnetron sputtering. The x-ray diffraction (XRD) patterns presented the crystal structures of ZnO:In films, while transmission spectra and photoluminescence (PL) spectra showed the changed band gap and the visible emission from defects, as compared to the PL spectra of undoped ZnO films. It was concluded that the increase of substrate temperature enhanced the crystal quality of ZnO:In films; the incorporation of In made the c-axis constant of the samples larger than that of undoped ZnO films; the blue emission was due to the transition from an unknown donor level by indium doping to the valance band; and the orange-green emission originated from acceptor defects (O Zn ) formed in the O-rich plasma. Meanwhile, the currentvoltage characteristics and persistent photoconductivity phenomenon also could be explained by the increased acceptor defects (O Zn ) that formed when the substrate temperature was increased.

Physical properties and growth kinetics of co-sputtered indium-zinc oxide films

“…The optical band-gap energies are obtained directly from the x intercept of a linear fit to the absorption curve [22], which are 3.24 eV, 3.16 eV, 3.08 eV and 2.97 eV corresponding to the sample of ZnO, IZO-1, IZO-2 and IZO-3, respectively. It is indicated that the optical band-gap energy shifts to lower energy sides as the In dopant concentration increases, which is consistent with the results reported by Li [23]. This may be due to the electron-ion and electron-electron scattering induced narrowing of optical band gap [24] or the lattice expansion from the large In atoms instead of small Zn atoms.…”

The Effect of Oxygen-Rich Condition on Properties of ZnO: In Films by Sputtering

“…In sample b, the current density turned from 0.06mA•cm -2 into highest value 6.58mA•cm -2 for 590s, and decreased to 0.84mA•cm -2 after an hour. According to the former results, it was ascribed V O defect as trap center in PPC phenomenon [4,20], which was different from our report on high-temperature sample [19]. Because in sample b the effect of crystal boundary on carrier scattering was weak, the current density was higher than that of sample a.…”

“…This curve indicated that the donor defect was still dominant defect in ZnO:In films. Some shallow acceptor donor defect made the formation Fermi level move away from conduction band edge, and there was no spike in the interface [19]. At last it was measured the photoconductivity of ZnO:In films deposited on SiO 2 /Si substrate.…”

The effects of post-thermal annealing on the optical parameters of indium-doped ZnO thin films

“…4. Li et al [19] obtained a similar band gap value (3.11 eV-3.26 eV) for ZnO:In thin films deposited by DC reactive magnetron sputtering. Figures 5 and 6 present the dependences of the dielectric constant on the wavelength of the ZnO:In thin film before and after annealing at different temperatures, each as a function of wavelength.…”