Synthesis of room temperature photoluminescence thin films and their evaluation

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Results obtained 1998-1999 are as follows.(1) Synthesis of CdWO4 thin films was successful on glass substrate by pulsed laser deposition (PLD) using mixed oxide targets CdO and WO3. They showed photoluminescence at room temperature. Results are published, Followings are obtained based on this research subject.(a) Conditions in PU) of CdWO4 such as laser spot size, laser fluence, ambient oxygen pressure, target-substrate distance, substrate temperature were studied. Good crystalline thin films were obtained after high temperature annealing. It is suggested that CdWO4 dusters are synthesized in plume formed in PLD and are deposited on the substrate. Intense photoluminescence intensity at room temperature was obtained with their crystalline growth.(b) PU) of single crystal CdWO4(0l0) was carried out on zeolite substrates. CdWO4 duster generation was suggested from XRD, SEM and EPMA data. It was made dear that there are two photo-luminescence channels in CdWO4 and low wavelength component was mainly observed on the clusters.(c) This new synthesis method using PU) was applied to another mixed oxide thin films. Synthesis of CaWO4 thin films using CaO and WO3 targets was succeeded by PU). They showed photoluminescence properties at room temperature. Results are under preparation for publication.(2) Some Si dusters were prepared on Teflon substrate by PUD of Si target under UHV system. They were characterized with XPS and UPS.They contained oxygen atoms with composition Si3-40. It was found that their work functions are smaller than Si crystal surface. Results are accepted in Applied Surface Science.(3) PUD of Si was carried out in the presence of NH3. They were studied with UPS and XPS.Results are published. Room temperature stable N-terminated Si clusters were prepared by laser annealing. They showed green photoluminescence at room temperature. Results are under preparation for publication.