Yutaka Hattori

SATELLITE PEAK GENERATION IN THE ELECTROLUMINESCENCE SPECTRUM OF ZNS:SM GROWN BY METALORGANIC CHEMICAL VAPOR DEPOSITION WITH CL CODOPING

ZnS:Sm, ZnS:Sm,Cl, and ZnS:Cl thin films were grown by metalorganic chemical vapor deposition using the thd‐chelate (thd=2,2,6,6‐tetramethyl‐3,5‐heptanedione) of Sm and hydrogen chloride. The electroluminescence spectrum of the ZnS:Sm,Cl showed three satellite peaks appearing in each of the 7 nm ranges around the three dominant peaks that the ZnS:Sm has originally. The ZnS:Sm,Cl also showed photoluminescence attributed to the self‐activated centers, but its intensity was less than 10−2 of that of the ZnS:Cl. The effect of the Cl codoping on Sm3+ luminescent properties is discussed on the basis of the Sm‐VZn (zinc vacancy)‐Cl complex formation.

EL displays for automotive applications

This paper presents an overview of the display requirements for automotive applications and introduces alternating-current thin-film electroluminesent (ACTFEL) displays for automobiles. An ACTFEL has advantages over other displays under sunlight and low temperature conditions. Several automotive applications for transparent and multicolor EL displays are introduced in this paper.

34.1: Invited Paper: Reduction of Halo in Transparent Electroluminescent (EL) Display

Recently, a variety of information is displayed in automobiles. One of the elements which is expected to be used for display of information is the transparent EL display. However, this display generates a phenomenon called “halo”, which causes the area around the emitter to blur and gleam, resulting in decrease of visibility. In this research, we elucidated the mechanism of how this phenomenon occurs, and reduced the relative halo luminance ratio (i.e. halo luminance of adjacent pixels / luminance of illuminating pixels) from 3.6% to 1.7%. This has made possible the materialization of a dual vision optitron meter, which is a device combining analog meters with digital meters having a transparent EL panel (dual vision optitron meter is a registered trademark).

Multi-Gas Sensor by Infrared Spectrometer

In order to detect many types of gases (CO2, NOx, SOx, C2H5OH) in the automotive cabin by infrared absorption sensor, we developed a novel micro electro mechanical systems (MEMS) based Fabry–Perot spectrometer with an ultra wide wavelength range (3.20–8.40 μm) compared to previously reported spectrometers (typically 2.80–5.80 μm). The wavelength range of a Fabry–Perot spectrometer is known to increase by increasing the ratio of the refractive indices of the multilayer mirrors. Thus, a novel mirror structure was proposed replacing the low refractive index layer of SiO2 (nL = 1.44) with “air (nL = 1.00)” for a wider wavelength range. To fabricate the proposed structure, the internal stress of the four ultra-thin polycrystalline silicon films (ca. 320 nm) was controlled tensile by the deposition temperature. A gas sensor was fabricated using our developed spectrometer. It was found that the sensor detected CO2 and C2H5OH successfully.