Study On The Effect Of Crystallization Conditions On Gallium Crystal Growth

As a kind of electronic material with excellent properties,gallium is now an absolutely necessary basic resource to produce semiconductors.Along with the rapid development of LED,solar power and information technology,the demand for gallium has been dramatically increased in China and abroad,and the requirements of its purity are much stricter than ever before.Among all the purification methods,the crystallization method has certain advantages,such as less energy cost,simple processes and better purifying results,which has attracted more and more attention.In order to improve the purification of gallium,our research,according to principles of crystal nucleation and growth,mainly focused on the effect of crystal crystallization technological parameters on gallium crystallization.By producing crystal seeding in different conditions,the research studied the influence of crystal seeding's shape and gain-number on the gallium crystallization.With certain seeding,the influence of cold junction temperature,crystallization time and crystallization device's shape on the morphology and crystallization speed were studied.In conclusion,the best process was chosen to purify the gallium and analyze the purity to calculate the effective distribution coefficient.Experiment results showed that the crystal seeding with rhombus,polygon,irregular shapes could be obtained in condition of holding 30,40 and 50 min under 40?&45?.The rectangle seeding was obtained only in the condition of holding 50 min under 45?.Only the rhombus seeding could induce structured shapes.Shapes of seedings had no influence on crystallization rate with the same temperature and time.With seeding-number increased,the gallium lost its structured shape,but it didn't affect the crystallized rate.The gallium had the most structured shape with one seeding.The cone bottom device could optimize the growth direction,where the structured crystal can be obtained.Along with the decrease of the temperature,the morphology of crystallized gallium in regular bottom device became irregular and the original smooth interface structure turned into rough at 24?.On the contrary,the morphology of gallium in cone bottom device kept structured.The relationship of the crystallization rate and time is linear in both devices,which proved its growth pattern is continuous growth,only the speed became lower after 6 hours in cone bottom device.The sum of impurities in gallium after 6 hours and 9 hours was 0.1415ppm and 2.0263 ppm.The purity of gallium both could achieve 99.999%,in the cold junction temperature of 28?;the change of crystallization rate leads to the difference of effective distribution cofficient.