Erbium-doped indium oxide films prepared by radio frequency sputtering

Abstract

Er doping of conducting oxide films has been investigated. Erbium-doped indium oxide films were prepared by rf magnetron sputtering. The deposited films were characterized in terms of electrical, optical, and structural properties. The Er-doped indium oxide films are highly (222)-oriented normal to the substrate surface and show a resistivity in the range of 10−3–103 Ω cm. The Er-doped conducting (or semiconducting) oxide films are optically active, i.e., show a clear room-temperature photoluminescence at 1.54 μm, corresponding to intratransitions in Er3+ ions. Compared with the undoped indium oxide films, the erbium doping is found to have the effect of increasing the resistivity (up to two orders of magnitude) of the films, mainly via a reduction of carrier concentration. Post-deposition annealing in air ambient significantly enhances both the Er3+ luminescence and Hall mobility (up to 60 cm2/V s), and reduces the carrier concentration. The enhancement of Hall mobility is attributed to a reduction of grain boundaries and voids with the anneal treatment as supported by the x-ray diffraction measurement results. Post-deposition annealing in reducing ambient (N2/H2) decreases the resistivity dramatically, mainly via an increase of carrier concentration (up to 1020 cm−3), and also enhances the Er3+ luminescence.