| 摘要 |
PURPOSE:To enable precise control of thermal environment and to improve the quality of a single crystal of a compd. having high dissociation pressure by sensing the temp. of the surface of the melt optically through an optical window comprising a light transmittive material, and controlling a heating source basing on the sensed result. CONSTITUTION:GaAs is synthesized directly in a vessel contg. gaseous As sealed therein from Ga and As charged in a crucible 11. Then, a GaAs single crystal is pulled up. During this procedure, a tip of a quartz rod 1 for an optical window is held always at ca. 850 deg.C, and an clouding is caused on the rod. The indication of a two wavelength radiation pyrometer 2 shows maximally ca.+ or -5 deg.C variation influenced by the fluctuation of the temp. of the melt surface, but the mean value of the temp. after the pulling is commenced and the single crystal entering the straight barrel part, is held at + or -1 deg.C. As the result, a uniform crystal is obtd. The compd. having high dissociation pressure to be prepd. by this method is, for example, InAs, etc. in addition to the above descirbed GaAs. |
