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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.

众所周知，脉冲激光烧蚀（PLA）在沉积过程中具有相当独特的特点，即沉积颗粒由微米级的原子种类、团簇和熔滴组成。本研究的目的是研究使用熔融液滴的 PLA 沉积薄膜的制造过程。在PLA工艺中，人们一直认为必须消除液滴。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，使用大量熔滴通过 PLA 进行晶体生长将是一项有吸引力的技术，它允许使用类似 VPE 的真空系统生长类似 LPE 的晶体。首先，本研究采用了锗 (Ge)。采用 YAG 激光（532 nm）的二次谐波有效地产生 Ge 液滴。发现在室温下制备的Ge薄膜在基底上有大量的固化液滴。当衬底温度升高到600℃时，在(100)Si衬底上形成岛状Ge薄膜。 X射线极图测量表明，Ge薄膜显示出Ge晶体以立方体叠加立方体的方式在平面内和平面外排列的生长。钇铁石榴石（YIG）是本研究的第二个目标。 YIG 被认为是微波应用的优异材料。 YIG 薄膜是使用 YAG 激光器通过 PLA 在 (111)GGG 基底上生长的。使用大量熔融液滴，在 PLA 加热到 860 ℃ 的 (111)GGG 基底上生长出高度取向的 YIG 晶体，这表明类似 LPE 的生长。该 YIG 薄膜显示出 7.5 Oe 的小铁磁共振线宽。对于气相外延技术制备的薄膜来说，这个值相当小。