稲富 裕光

資料番号: AA0063349113

第22回宇宙利用シンポジウム(2006年1月17日-19日, 日本学術会議6階会議室 六本木、東京)共催: 日本学術会議資料番号: AA0064113011

第22回宇宙利用シンポジウム(2006年1月17日-19日, 日本学術会議6階会議室 六本木、東京)共催: 日本学術会議資料番号: AA0064113001

本報告では,半導体結晶の溶液成長過程における以下の研究成果を述べる.(1)半導体結晶の溶液成長過程における固液界面の形態変化に及ぼす基板結晶の面方位の影響を調べるために近赤外顕微鏡を使ったその場観察実験が実施された.その結果,対流を抑制することでGaP/GaP成長界面のステップカイネティクス係数の面方位依存性が得られ,結晶成長時におけるマクロステップの挙動が評価された.また,GaAs_xP_<1-x>/GaPヘテロLPE 成長初期の固液界面の表面形態変化が基板表面の面方位依存性の視点から議論された.(2)静磁場THM 法によりTe 溶液から育成したCdZnTe 結晶の成長界面が急冷法によって調べられた.その結果,浮力対流を抑制することで速い引き下げ速度でも良質なCdZnTe 成長結晶を得られることを示した.

In situ observations were carried out in faceted transparent organic materials grown unidirectionally by multiwavelength interferometry, which enabled us to measure the distribution of temperature and solute concentration distributions in the liquid in the vicinity of the solid/liquid interface simultaneously. The aim of the experiments was to reveal a mechanism of a faceted cellular array growth taking account of an influence of latent heat of fusion of the material upon a temperature distribution in the melt. Some experimental results were briefly summarized in the present report.

The purpose of the present study was to investigate a suitable condition to damp the convection in order to measure a reliable diffusion coefficient in electrically conducting liquid under the terrestrial condition by utilizing a static magnetic field based on a numerical simulation. Consequently, application of an axial magnetic field is not effective to damp effect on the convection in melt with high aspect ratio.

Under the microgravity environment, it is considered that thermal convection is suppressed. Therefore, diffusion becomes the main factor of material transport. Thus it is expected that one can synthesize materials with fewer defects or unique structures and get new information about the growth mechanism of materials. Diamond possesses superior properties, for example, high hardness, high thermal conductivity, high transparency, high electron and hole mobilities, and a wide bandgap. These unique properties suggest many potential applications. The conventional techniques for depositing diamond at low pressure utilize a flow of a hydrocarbon-hydrogen gas mixture with complicated gas tubing for introducing the reaction gas into a reaction chamber and evacuating reactant gas from it. For few years, one of us (YT) had been concentrated on developing completely closed diamond synthesizing system aimed for microgravity conditions. With our experiments, we successfully confirmed that diamond was synthesized with this completely closed system, and that this system was very suitable for mounting on large centrifuges and in spacecraft.

In this research, the morphological changes during GaP LPE growth of the S/L interface were observed under strong static magnetic field using near-infrared microscopic interferometer. We discussed the damping effect of convection on the surface morphology during dissolution and growth.

The concentration distribution change in a hen-egg-white lysozyme solution was measured in situ using a microscopic interferometry to investigate the influence of the magnetic field on the process of protein crystal growth. It was found that highly oriented lysozyme crystals were obtained under a magnetic field without any apparent change of solubility. Some influences on the growth kinetics in the early stages of the crystal growth were also found in this research.

In situ observation experiments of GaAs_xP_<1-x>/GaP LPE growth were performed to investigate the influence of the surface orientation of the substrates upon the morphological change at the early stage of the growth.