The possibility for white light emitting devices using carbon nitride (CNx) thin films has been studied. Microwave ECR-plasma CVD and RF-sputtering apparatuses have been used for the formation of CNx thin films. In both cases, CH4 was used as the source or sub-source of carbon in order to investigate the effect of hydrogenated carbon nitride for luminescence. The cathodeluminescence (CL) measurement of the film grown by ECR-plasma CVD method showed three peaks of R/G/B. The photoluminescence (PL) measurement of the film grown by RF-sputtering also showed the red peak, which could not be observed in the film without hydrogen. Together with the X-ray Photoelectron Spectroscopy (XPS) analysis data, we concluded that the red peak originates from C-H bonds and blue peak from C-N bonds.
Tb-doped AlBNO (AlBNO:Tb) films with various composition ratios are investigated for luminescence layers of inorganic electroluminescence(EL) devices. Luminescence layers with a wide bandgap and a low dielectric constant are required to realize high performance of EL devices. The ultraviolet-visible radiation absorption measurement and capacitance-voltage (C-V) measurement show that the AlBNO:Tb films have wider bandgap and lower dielectric constant than ZnS which is put to practical use as the host material of the luminescence layer. Photoluminescence (PL) measurement indicates that PL intensity increases with increasing B composition ratio in the range of 5 % -10 %. Moreover, the suppression factor of the PL intensity can be understood through the annealing experiment. The PL intensity of the film with 800 °C annealing is about 10 times larger than that of the film without annealing. X-ray photoelectron spectroscopy (XPS) measurement suggests that Tb 4+ ions decrease compared with Tb 3+ ions after annealing treatment. O atoms in the AlBNO:Tb film are dissociated from Tb and bonded to B atoms by annealing treatment. This suggests that decrease of Tb 4+ ions is related to increase of the PL intensity.
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