Electroluminescence color tuning between green and red from metal-oxide-semiconductor devices fabricated by spin-coating of rare-earth (terbium + europium) organic compounds on silicon

Color tunable electroluminescence (EL) from metal-oxide-semiconductor devices with the rare-earth elements Tb and Eu is reported. Organic compound liquid sources of (Tb + Ba) and Eu with various Eu/Tb ratios from 0.001 to 0.4 were spin-coated on an n+-Si substrate and annealed to form an oxide insul...

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Bibliographic Details
Published in:Japanese Journal of Applied Physics 2018-04, Vol.57 (4S), p.4
Main Authors: Matsuda, Toshihiro, Hattori, Fumihiro, Iwata, Hideyuki, Ohzone, Takashi
Format: Article
Language:English
Subjects:
Chromaticity
Color
Electroluminescence
Europium compounds
Hot electrons
Metal oxide semiconductors
Organic compounds
Rare earth compounds
Semiconductor devices
Silicon compounds
Silicon substrates
Spectrum analysis
Spin coating
Terbium
Transmission electron microscopy
X ray photoelectron spectroscopy
X-ray diffraction
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Summary:Color tunable electroluminescence (EL) from metal-oxide-semiconductor devices with the rare-earth elements Tb and Eu is reported. Organic compound liquid sources of (Tb + Ba) and Eu with various Eu/Tb ratios from 0.001 to 0.4 were spin-coated on an n+-Si substrate and annealed to form an oxide insulator layer. The EL spectra had only peaks corresponding to the intrashell Tb3+/Eu3+ transitions in the spectral range from green to red, and the intensity ratio of the peaks was appropriately tuned using the appropriate Eu/Tb ratios in liquid sources. Consequently, the EL emission colors linearly changed from yellowish green to yellowish orange and eventually to reddish orange on the CIE chromaticity diagram. The gate current +IG current also affected the EL colors for the medium-Eu/Tb-ratio device. The structure of the surface insulator films analyzed by cross-sectional transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, and X-ray photoelectron spectroscopy (XPS) has four layers, namely, (Tb4O7 + Eu2O3), [Tb4O7 + Eu2O3 + (Tb/Eu/Ba)SiOx], (Tb/Eu/Ba)SiOx, and SiOx-rich oxide. The EL mechanism proposed is that electrons injected from the Si substrate into the SiOx-rich oxide and Tb/Eu/Ba-silicate layers become hot electrons accelerated in a high electric field, and then these hot electrons excite Tb3+ and Eu3+ ions in the Tb4O7/Eu2O3 layers resulting in EL emission from Tb3+ and Eu3+ intrashell transitions.
ISSN:0021-4922
1347-4065
DOI:10.7567/JJAP.57.04FH05