The papers, which were reported at the 7th International Workshop on Electroluminescence (EL-94) and at the International Symposium on Inorganic and Organic Electroluminescencc, were summarized. Recent progress in color thin-film EL displays was reviewed. New blue EL phosphors, which are used for the color EL display with patterned R/G/B phosphor structure, and white EL phosphors, which are used for the color EL display with patterned R/G/B filtered structure, were discussed. Many papers discussed electrical characterization of EL devices ad basic physics of high field EL. Recent progress in organic EL devices was also reviewed. It was reported that EL characteristics of organic EL devices with evaporated organic dye thin films meet the requirement for practical applications, and that rapid progress has been done on polymer electroluminescence.

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A new thin-film electroluminescent (TFEL) device using a manganese-activated zinc gallate (ZnGa_2O_4 : Mn) phosphor has been developed. A TFEL device with an as-deposited ZnGa_2O_4 : Mn thin-film emitting layer prepared by rf magnetron sputtering exhibited a weak green EL emission with a luminance of 0.02 cd/m^2. A luminance of 630 cd/m^2 and a maximum luminous efficiency of 0.9 lm/W, and a luminance as high as 200 cd/m^2 were obtained in TFEL devices with the thinfilm emitting layers postannealed at 1020℃, driven by 1 kHz and 60 Hz sinusoidal wave voltages, respectively.

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The surface of ZnS flourescence powders is coated with silicon dioxide (SiO 2) films by the photochemical vapor deposition (Photo-CVD) using disilane (Si 2H6) and oxide (O2) at low temparature in order to elongate the EL device life. The results of this study are as follows. (1) ZnS flourescence powders is coated with SiO 2 films at very low temperature compared with that in chemical vapor deposition (CVD), and the EL device life was improved. (2) The shift of the emission spectrum of the EL device with the treated ZnS flourescence powder was reduced. (3) The emission waveform of the EL device with the treated ZnS flourescence powder was changed.

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Thin film electroluminescent devices (TFELD) have been actively investigated. We studied on the ZnS thin films, which are used as the active layer of the TFELD, by ion beam sputtering under various impurity (SmF_3) concentration of the target and sputtering gas composition (Ar : O_2). As a result of experiments, the oxygen concentration in the sputtered ZnS thin films was increased and the lattice constant of the ZnS thin films was decreased with increasing O_2 partial preasure. The brightness of the TFELD using these ZnS thin film was increased with increasing O_2 partial preasure.

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We have fabricated dc-driven ZnS/p-Si thin film electroluminescence devices by the ion beam sputtering method. The interface states of ZnS/p-Si which have effects on the luminescent properties have been investigated qualitatively using the conductance technique. It was found that the density of interface states had been increased by annealing. But the density of interface states are low so that the current density-voltage characteristics did not changed for the interface states at both before and after annealing. It have been also studied for the case of ZnS thin film doped with Sm, F. The density of interface states was same as the case for non-doped ZnS thin film.

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New driving method has been developed to improve the luminance of EL panels. This method uses additional pulses, which are added to symmetric drive pulses in the every field of Push-Pull drive method. Increase of the luminance due to the additional pulses results from the polarization charge generated by drive pulses. To evaluate the advantage of this new driving method, we have measured EL characteristics of ZnS : Mn thin film EL devices by using the driving pulse waveforms, which simulated the new driving method. We have also examined this method for commercial ZnS : Mn thin film EL panels.

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Organic thin film EL devices have been extensively investigated in recent year. We synthesized N, N'-diphenyl-N, N'-bis (3-methyl phenyl) 1,1'biphenyl-4,4'-diamine (TPD). We fabricated thin film double-layer structure utilizing Alq_3 as an emitting layer and TPD as a hole transport layer by vapor deposition. We exmined the effect of the hole transport layer on the EL devices. In addition, we measured deterioration characteristics of the devices.

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The reflector type LED (Light Emittins Diode) has a structure to emit the light from the LED chip with a high efficiency. This report explain the structure and the optical efficiency of the lens type LED which is used generally, then it explains the structure and the optical efficiency of the reflector type LED.

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Up to the present several kinds of prototype FEDs were made, the FED has been taken an extreme interest for practical use, e.g. display of a portable information machine. In the present paper, we fabricated the field emitter arrays (FEAs) made of n-type silicon covered with the metal by photolithography. We measured the energy distribution of the field emitted electrons by an ac retarding field method.

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