A high-luminance green-emitting electroluminescent (EL) device fabricated using a manganese-activated zinc gallate ( ZnGa2O4:Mn) thin-film phosphor in conjunction with a thick barium titanate ceramic insulator has been demonstrated. The green emission was observed in EL devices fabricated using as-deposited ZnGa2O4:Mn thin films prepared by rf magnetron sputtering. A higher luminance was attained for EL devices fabricated using ZnGa2O4:Mn thin films postannealed at 1020° C in an argon atmosphere. A luminance of 710 cd/m2 and a maximum luminous efficiency of 1 lm/W were obtained for a ZnGa2O4:Mn thin-film EL device driven by a sinusoidal voltage at 1 kHz. The device when driven at 60 Hz exhibited a luminance of 230 cd/m2.

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ZnGa2O4:Mn thin films as the emitting layer in thin-film electroluminescent (TFEL) devices have been prepared by rf magnetron sputtering and low-pressure chemical vapor deposition (CVD). The as-deposited thin films, regardless of preparation methods, were ZnGa2O4 which crystallized with a spinel structure. A green EL emission was realized in TFEL devices using as-deposited ZnGa2O4:Mn thin films as the emitting layer and a thick BaTiO3 ceramic sheet as the insulating layer. Maximum luminances of 0.7 and 7.6 cd/m2 were obtained in TFEL devices using as-deposited ZnGa2O4:Mn thin films prepared by the sputter and CVD techniques, respectively, when driven by a sinusoidal wave voltage at 1 kHz. In addition, a maximum luminance above 600 cd/m2 was obtained in TFEL devices using ZnGa2O4:Mn thin films postannealed at a temperature of about 1000 °C, regardless of preparation methods. The improvement of EL characteristics by postannealing ZnGa2O4:Mn thin-film emitting layers was mainly attributed to an improvement in the crystallinity of the emitting layers.

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Abstract— EL characteristics of single‐insulating‐layer type TFEL devices with a Zn2SiO4: Mn or ZnGa2O4: Mn phosphor thin‐film emitting layer have been described in comparison with those of a ZnS:Mn TFEL device. Unsealed, these devices were life‐tested under room‐temperature operation in the atmosphere. Differences in the degradation mechanism and EL characteristics between the Mn‐activated sulfide and oxide phosphor emitting layers were observed. The oxide phosphor emitting layers were stable in comparison with the ZnS:Mn thin‐film emitting layer, for use in the atmosphere. It can be concluded that green‐emitting ZnGa2O4: Mn oxide phosphor is very stable for use as the emitting layer of TFEL devices.