STUDY OF HEAT AND MASS TRANSPORT PHENOMENA IN CRYSTAL GROWTH

Following the recent progress of technology，crystal materials with better quality and improved properties are strongly demanded.In order to realize technological break-throughs in this area，understanding of several phenomena relating to the crystal growth process，especially mass and heat transport phenomena，is most important.In this work，the investigation of heat and mass transport phenomena，and the pursuit of means to control them，have been carried out.The following topics have been mainly investigated by exchanging researchers between Japan and Germany。·heat and mass transport phenomena accompanied with semiconductor crystal growth by the LEC，MCZ and FZ technique，·distribution of impurities and dopants during the growth of oxide and fluoride single crystals，In all，6researchers from Japan visited Germany and 7researchers from Germany visited Japan over the two years of exchanges.One of the most successful results as the growth of fluoride single crystals，the most successful results as the growth of fluoride th.Although the growth of fluorides has been recognized as difficult because of the use of highly toxic HF gases，we have successfully grown a series of high-quality Corquillite-type crystals，such as Ce：LiSAF and Ce：LiSAF.Grown Ce：LiCAF crystals showed60mJ laser output energy in the UV wavelength region。This is the highest power ever reported.By this international collaboration，we have successfully established stronger international relations for research.This led us to hold the“Japan-Germany Meeting for Crystal Growth”in the beginning of 1998。Since this meeting was well-received，the 2nd meeting including Poland is now being planned for the beginning of 1999.This research work also allowed us to invite Prof.Peter Rudolph，IKZ，and Dr.Boris Epelbaum，IKZ，as visiting professor and visiting associate professor，respectively，at the Institute for Materials Research，Tohoku University，each for 3months.

Following the recent progress of technology, crystal materials with better quality and improved properties are strongly demanded. In order to realize technological break-throughs in this area, understanding of several phenomena relating to the crystal growth process, especially mass and heat transport phenomena, is most important. In this work, the investigation of heat and mass transport phenomena, and the pursuit of means to control them, have been carried out.The following topics have been mainly investigated by exchanging researchers between Japan and Germany.・ heat and mass transport phenomena accompanied with semiconductor crystal growth by the LEC, MCZ and FZ technique,・ distribution of impurities and dopants during the growth of oxide and fluoride single crystals,In all, 6 researchers from Japan visited Germany and 7 researchers from Germany visited Japan over the two years of exchanges.One of the most successful results was the growth of fluoride single crystals and the development of the needed crystal growth technology. Although the growth of fluorides has been recognized as difficult because of the use of highly toxic HF gases, we have successfully grown a series of high-quality Corquillite-type crystals, such as Ce : LiSAF and Ce : LiSAF.Grown Ce : LiCAF crystals showed 60 mJ laser output energy in the UV wavelength region. This is the highest power ever reported.By this international collaboration, we have successfully established stronger international relations for research. This led us to hold the "Japan-Germany Meeting for Crystal Growth" in the beginning of 1998. Since this meeting was well-received, the 2nd meeting including Poland is now being planned for the beginning of 1999.This research work also allowed us to invite Prof.Peter Rudolph, IKZ, and Dr.Boris Epelbaum, IKZ, as visiting professor and visiting associate professor, respectively, at the Institute for Materials Research, Tohoku University, each for 3 months.