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PREPARATION OF HIGH-QUALITY ELECTRONIC THIN FILMS BY LASER DROPLET EPITAXY

激光微滴外延制备高质量电子薄膜

基本信息

批准号：
10450006
负责人：
MORIMOTO Akiharu
金额：
$ 8.64万
依托单位：
KANAZAWA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10450006/
关键词：
PULSED LASER ABLATION PULSED LASER DEPOSITION LASER DROPLET EPITAXY YAG LASER GERMANIUM SILICON YTTRIUM IRON GARNET GADOLINIUM GALLIUM GARNET レーザアブレーションドロプレットエピタクシイットリウム鉄ガーネット薄膜ガドリニウムガリウムガーネット基板 PLD 磁気共鳴半値幅ゲルマニウム薄膜温度シ

项目摘要

Pulsed laser ablation (PLA) is known to have quite unique features in deposition process, I.e., the depositing particles consist of atomic species, clusters, and molten droplets with micron size. The aim of this study is to investigate the fabrication process of thin-film depositions by PLA using the molten droplets. In PLA process, it has been believed that droplets must be eliminated. Liquid phase epitaxy (LPE) is equilibrium process, while vapor phase epitaxy (VPE) is non-equilibrium process. In order to grow a high quality film with a low defect density, crystal growth by PLA using large number of molten droplets will be an attractive technique that allows LPE-like crystal growth using VPE-like vacuum system.First, germanium (Ge) was employed for this study. The second harmonic of YAG laser (532 nm) was employed for producing Ge droplets efficiently. Ge film prepared at room temperature was found to have a large number of solidified droplets on the substrate. As the substrate temperature was elevated up to 600 ℃ , Ge film was formed as island structure on (100)Si substrates. The x-ray pole figure measurement revealed that Ge film showed growth of Ge crystal aligned in plane as well as out of plane in a manner of cube-on-cube.Yttrium Iron Garnet (YIG) was the second target for this study. YIG is known to be a excellent material for microwave applications. YIG films were grown by PLA on (111)GGG substrates using the YAG laser. Highly oriented YIG crystal were grown on the (111)GGG substrate heated at 860 ℃ by PLA using a large number of molten droplets, suggesting an LPE-like growth. This YIG films shows a small ferromagnetic resonance linewidth of 7.5 Oe. This value is quite small for films prepared by vapor-phase epitaxy techniques.

脉冲激光烧蚀（PLA）在沉积过程中具有非常独特的特征，即，沉积颗粒由微米尺寸的原子种类、团簇和熔融液滴组成。本研究旨在探讨聚乳酸熔滴沉积薄膜的制程。在PLA工艺中，人们认为必须消除液滴。液相外延（LPE）是平衡过程，而气相外延（VPE）是非平衡过程。为了生长具有低缺陷密度的高质量薄膜，使用大量熔融液滴通过PLA进行晶体生长将是一种有吸引力的技术，可以使用类似VPE的真空系统进行类似LPE的晶体生长。首先，锗（Ge）用于本研究。采用YAG激光的二次谐波（532 nm）有效地制备Ge液滴。发现室温下制备的Ge薄膜在衬底上有大量的凝固液滴。当衬底温度升高到600 ℃时，Ge薄膜在（100）Si衬底上形成岛状结构。X射线极图测量显示Ge薄膜以立方叠立方的方式在平面内和平面外取向生长。钇铁石榴石（YIG）是本研究的第二个目标。YIG是一种优良的微波应用材料。利用YAG激光器在（111）GGG衬底上用PLA法生长YIG薄膜。在（111）GGG基片上，采用大量的熔融液滴，在860 ℃加热的PLA溶液中生长出了高度取向的YIG晶体，表明是类液相外延生长。这种YIG薄膜显示出7.5 Oe的小铁磁共振线宽。这个值对于气相外延技术制备的薄膜来说是相当小的。