Growth and characterization of Mn-doped In2O3 nanowires and terraced microstructures

Mn-doped In2O3 micro- and nanostructures were grown by the thermal evaporation–deposition method using a precursor powder composed of In2O3 and a manganese compound. Terraced microstructures grow at 1200 °C when using Mn2O3 in the precursor powders, while thinner micro- and nanowires have been obtained at temperatures between 560 and 780 °C by using MnCO3 in the precursor mixture. The morphology, as well as the luminescencent, electrical and chemical properties, of the Mn-doped In2O3 micro- and nanostructures were characterized by means of X-ray diffraction, scanning electron microscopy, electron backscattered diffraction, cathodoluminescence (CL), energy dispersive X-ray spectroscopy, remote electron beam induced current (REBIC) and X-ray photoelectron spectroscopy (XPS). The amount of Mn incorporated in these low-dimensional structures is below 1 at.%. The Mn-doped In2O3 structures show luminescence at 1.91 and 2.27 eV, related to defects associated with an excess of oxygen and single ionized oxygen vacancies (VO+), respectively. An emission at 2.94 eV, possibly due to the direct band gap of In2O3, has been also observed. The presence of VO+, which tend to accumulate at the edges of the terraces of the microstructures, has been traced by combined CL–REBIC–XPS techniques, and has been related to the incorporation of manganese as Mn2+.