Abstract
High quality In2O3 films are grown by chemical vapor transport and condensation using high purity commercial In2O3 and ZnO powders as starting materials, under an Ar/O-2 gas mixture. The cubic structure of the In2O3 films is determined by x-ray diffraction and Raman spectroscopy. At 300 K, the photoluminescence (PL) results from In2O3 films display only an intense deep level emission line centered at 1.968 eV, similar to that obtained from the commercial In2O3 powder. In the UV range, 5 K PL measurements of the films reveal sharp lines which are not observed on the 5 K PL spectrum from commercial In2O3 powder. The dominating peak at 3.3672 eV, as well as energy differences of 72 meV between lines are characteristic of ZnO and correspond to a neutral donor bound exciton ((DX)-X-0) emission and the energy of the LO phonon in ZnO, respectively. In comparison to the (DX)-X-0 line position from ZnO nanostructures, this (DX)-X-0 line displays a blueshift of 8 meV which is well explained by a quantum confinement of ZnO nanocrystallites in In2O3. Low temperature PL measurements reveal ZnO nanocrystallites embedded in In2O3 film, which are not observed by either x-ray diffraction and Raman spectroscopy. (C) 2008 American Institute of Physics. [DOI:10.1063/1.3000463]