Transparent amorphous oxide semiconductor thin film phosphor, In-Mg-O:Eu

Abstract

We succeeded in fabricating light-emitting amorphous oxide (LEAO) thin films by doping Eu3+ ions to amorphous InMgO deposited at room temperature using (In,Eu)2MgO4 polycrystalline targets by pulsed laser deposition. Clearly visible photoluminescence (PL) with a peak at 615nm was observed at room temperature by 270nm light excitation even without postdeposition thermal annealing. The unusual variation of PL intensity with Eu concentration is understood in terms of nonradiative Auger recombination via conduction carriers. The PL intensity also exhibited maximums with respect to oxygen pressure during deposition (PO2) and annealing temperature (Ta), which are explained by recombination centers generated by oxygen deficiency-related defects at low PO2, by excess/weakly-bonded oxygen at high PO2, and by hydrogen depletion at high Ta. Since the LEAO films can be obtained even by room-temperature deposition, it is expected to have flexible optoelectronic applications using plastic substrates.