The formation and evolution characteristics of bcc phase during the isothermal relaxation processes for supercooled-liquid and amorphous Pb were investigated by molecular dynamics simulation and cluster-type index met...The formation and evolution characteristics of bcc phase during the isothermal relaxation processes for supercooled-liquid and amorphous Pb were investigated by molecular dynamics simulation and cluster-type index method （CTIM）. It is found that during the relaxation process, the formation and evolution of bcc phase are closely dependent on the initial temperature and structure. During the simulation time scale, when the initial temperature is in the range of supercooled liquid region, the bcc phase can be formed and kept a long time; while it is in the range of glassy region, the bcc phase can be formed at first and then partially transformed into hcp phase; when it decreases to the lower one, the hcp and fcc phases can be directly transformed from the glassy structure without undergoing the metastable bcc phase. The Ostwald＇s ＂step rule＂ is impactful during the isothermal relaxation process of the supercooled and glassy Pb, and the metastable bcc phase plays an important role in the precursor of crystallization.展开更多
A series of hydrogenated silicon thin films were prepared by the radio frequency plasma enhanced chemical vapor deposition method (RF-PECVD) with various si-lane concentrations. The influence of silane concentration o...A series of hydrogenated silicon thin films were prepared by the radio frequency plasma enhanced chemical vapor deposition method (RF-PECVD) with various si-lane concentrations. The influence of silane concentration on structural and elec-trical characteristics of these films was investigated to study the phase transition region from amorphous to microcrystalline phase. At the same time,optical emis-sion spectra (OES) from the plasma during the deposition process were monitored to get information about the plasma properties,Raman spectra were measured to study the structural characteristics of the deposited films. The combinatorial analysis of OES and Raman spectra results demonstrated that the OES can be used as a fast method to diagnose phase transition from amorphous to microcrystalline silicon. At last the physical mechanism,why both OES and Raman can be used to diagnose the phase transition,was analyzed theoretically.展开更多
基金Projects (50831003, 50571037) supported by the National Natural Science Foundation of China
文摘The formation and evolution characteristics of bcc phase during the isothermal relaxation processes for supercooled-liquid and amorphous Pb were investigated by molecular dynamics simulation and cluster-type index method （CTIM）. It is found that during the relaxation process, the formation and evolution of bcc phase are closely dependent on the initial temperature and structure. During the simulation time scale, when the initial temperature is in the range of supercooled liquid region, the bcc phase can be formed and kept a long time; while it is in the range of glassy region, the bcc phase can be formed at first and then partially transformed into hcp phase; when it decreases to the lower one, the hcp and fcc phases can be directly transformed from the glassy structure without undergoing the metastable bcc phase. The Ostwald＇s ＂step rule＂ is impactful during the isothermal relaxation process of the supercooled and glassy Pb, and the metastable bcc phase plays an important role in the precursor of crystallization.
基金Supported by the National Basic Research Program of China (Grant Nos. 2006CB202602 and 2006CB202603)
文摘A series of hydrogenated silicon thin films were prepared by the radio frequency plasma enhanced chemical vapor deposition method (RF-PECVD) with various si-lane concentrations. The influence of silane concentration on structural and elec-trical characteristics of these films was investigated to study the phase transition region from amorphous to microcrystalline phase. At the same time,optical emis-sion spectra (OES) from the plasma during the deposition process were monitored to get information about the plasma properties,Raman spectra were measured to study the structural characteristics of the deposited films. The combinatorial analysis of OES and Raman spectra results demonstrated that the OES can be used as a fast method to diagnose phase transition from amorphous to microcrystalline silicon. At last the physical mechanism,why both OES and Raman can be used to diagnose the phase transition,was analyzed theoretically.
