Indium Dopant Concentration Effects on Zinc Oxide Nanowires

We report in detail the effects of varying the concentration of indium as a dopant in ZnO on the structural, vibrational, and optical properties of ZnO nanowires. A highly versatile route to dope zinc oxide nanowires by using vapor-liquid-solid growth is employed. It is observed that the ratio of indium in ZnO reactant has a large impact on properties of indium-doped ZnO nanowires. Lower indium concentration reveals better transparency while higher concentrations of indium shows segregation of indium-rich domains within the doped nanocrystals. Photoluminescence measurements demonstrated band gap tuning and a smaller UV to deep emission ratio for doped nanowires. Phonon vibrational modes along with origin of observed anomalous vibrational modes induced due to indium incorporation in ZnO are discussed. An average transmittance of more than 90% is observed for a wide range of spectra in both visible and near-IR regions as compared with indium tin oxide. The lowest resistivity of 1.2 × 10^-3 Ω·cm was achieved for ZnO films doped with 7% indium oxide. These dramatically superior optical and electrical properties make it a superior candidate for various technological applications.