Synthesis of room temperature photoluminescence thin films and their evaluation

1998-1999年取得的成果如下。(1)采用脉冲激光沉积（PLD）技术，以CdO和WO 3为靶材，在玻璃衬底上成功地制备了CdWO 4薄膜。它们在室温下表现出光致发光。结果发表，以下是基于这个研究课题获得的。(a)研究了激光光斑尺寸、激光能量密度、氧分压、靶基距离、基片温度等工艺条件对CdWO_4薄膜制备的影响。高温退火后得到了结晶良好的薄膜。结果表明，CdWO_4簇粉是在PLD中形成的羽流中合成的，并沉积在衬底上。在室温下，它们的晶体生长得到了强烈的光致发光强度。(b)在分子筛衬底上制备了CdWO_4（010）单晶。XRD、SEM和EPMA数据表明CdWO_4粉末的产生。研究表明，CdWO_4团簇中存在两个光致发光通道，且团簇中主要存在低波长发光。(c)将这种新的合成方法应用于另一种混合氧化物薄膜。用CaO和WO_3靶成功地合成了CaWO_4薄膜。它们在室温下表现出光致发光性质。目前正在准备结果，以供发表。(2)在超高真空系统下，利用硅靶的PUD技术在聚四氟乙烯衬底上制备了硅粉末。用XPS和UPS对样品进行了表征，样品中含有氧原子，组成为Si 3 -40。发现它们的功函数都小于Si晶体表面。结果被应用表面科学所接受。(3)Si的PUD在NH3存在下进行。用UPS和XPS对它们进行了研究，并发表了结果。采用激光退火法制备了室温稳定的N端硅团簇。它们在室温下显示出绿色光致发光。目前正在准备结果，以供发表。

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.