Hiroshi Deguchi

Completely Erasable Phase Change Optical Disc II: Application of Ag–In–Sb–Te Mixed-Phase System for Rewritable Compact Disc Compatible with CD-Velocity and Double CD-Velocity

Aiming to obtain a rewritable compact disc (CD-rewritable) with high performance at both CD-velocity (CD1X) and double CD-velocity (CD2X), the phase change optical disc with the Ag-In-Sb-Te system has been developed. In the one-pass overwriting mode with eight-to-fourteen modulation, high carrier-to-noise ratio, wide power margin and high erase ratio have been obtained at both velocities. As for stability, we acquired a satisfactory result in the read-out test of 106 cycles with read power of 1.5 mW. We conclude that the phase change optical disc with the Ag-In-Sb-Te system is suitable for use at both CD1X and CD2X. Furthermore, the phase change process of the Ag-In-Sb-Te system has also been investigated. The chemical structure of the Ag-In-Sb-Te system in its ordered state was found to be (Ag-Sb-Te)x(In1-ySby)1-x.

White light emitting thin-film electroluminescent devices with SrS:Ce,Cl/ZnS:Mn double phosphor layers

White light emitting thin-film electroluminescent devices have been fabricated. The devices consist of double phosphor layers of a greenish-blue light emitting SrS:Ce, Cl and a yellowish-orange light emitting ZnS:Mn. A brightness level of 1100 cd/m2 at 5 KHz drive has been obtained.

Electroluminescence in thin‐film CaS:Ce

We report a double insulated CaS:Ce thin‐film electroluminescent (EL) device which emits a bright green EL due to Ce3+ luminescent centers, being characteristic of parity allowed 5d–4f transitions. A brightness level of 500 cd/m2 and emission efficiency of 0.11 lm/W have been obtained under 5‐kHz sinusoidal voltage excitation. The CaS:Ce thin film has been fabricated by coevaporation of CaS and sulfur.

Evaporated CaS thin films for AC electroluminescence devices

The growth behavior of evaporated CaS thin films has been investigated to achieve bright electroluminescence. The crystallinity of CaS films is improved with substrate temperature and for temperatures higher than 300°C, the films orient to the (200) plane. Sulfur coevaporation further helps to form a more perfect film even at lower temperatures. A CaS: Ce,Cl electroluminescent thin film device has been fabricated with a brightness of 650 cd/m2.

Inherent memory effect in a SrS:Ce,K blue‐emitting electroluminescent thin‐film device

The luminance‐applied voltage hysteresis characteristic, so‐called memory effect, has been found in the SrS:Ce,K blue‐emitting electroluminescent thin‐film device. The hysteresis voltage width is about 38 V with 1 kHz pulse drive. The origin of the memory effect is attributable to native defects of the SrS phosphors.