Epitaxial growth of the Mn-containing novel ternary compound MnGeP2 has been investigated. Prior to the growth experiments, theoretical studies using an ab initio calculation were carried out, on the basis of which the stable existence of MnGeP2 with a chalcopyrite structure was predicted. Growth experiments of Mn-Ge-P were performed on GaAs(001) and InP(001) substrates using a molecular beam epitaxy (MBE) technique, in which Mn and Ge were supplied from solid sources and P from a tertiary butyl phosphine (TBP) gas source. The optimum growth condition has been estimated on the basis of X-ray diffraction studies. Oriented overgrowth of MnGeP2 was confirmed from a reciprocal lattice mapping (RLM) on X-ray diffraction (XRD) analyses, and lattice constants have been determined to be a=0.569 nm and c=1.13 nm based on the assumption that the material has a tetragonal crystal structure.
A dynamic observation system for high speed crystallization has been developed using blue LD, high speed LD driver, streak camera and precise timing controller. We succeeded in dynamic observation of the crystal growth process of phase change materials induced by laser irradiation. The time-sequential development of crystallized region differs clearly between a eutectic composition Sb 78 Te 22 and a pseudo alloy Ge 2 Sb 2 Te 5 , and the growth rate of Sb 78 Te 22 crystal was determined to be at 0.28 m/s.1 Introduction Phase-change recording materials (e.g. GeSbTe) are gaining attention as rewritable high-speed optical disks [1] and phase-change RAM (PC RAM) recording materials. These materials change phase in less than a few tens of nanoseconds. The phenomenology in phase-change materials is simple and is based on differences in reflection or electric resistance of crystalline and amorphous phases. The crystal growth in phase change materials has been discussed in terms of reflectivity change in accordance with the phase transition from an amorphous to a crystalline state, thermal analysis, X-ray structural analysis, and the like [2,3]. The exact crystal growth process during the crystallizationamorphyzation process is still obscure. Recently Alexander V. Kolobov et al of AIST have reported from detailed XAFS and XANES analysis that the phase-change process is not a real phase transition from amorphous to crystalline material, but rather a change in the crystalline phase [4]. Nevertheless, there is still much that is unknown about dynamic crystal growth mechanisms.To observe high-speed transformation from the amorphous to the crystalline state of the phase change materials, we have developed a new prototype dynamic observation system. The crystal growth processes in Sb 78 Te 22 and Ge 2 Sb 2 Te 5 films induced by laser irradiation were observed.
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