| 摘要 |
PURPOSE:To grow a crystal of good quality efficiently from the beginning of the crystal up to the terminal part by decreasing the pulling up speed of the single crystal with a decrease in a melt surface. CONSTITUTION:In a pulling up method for single crystals such as single crystals of gadolinium, gallium and garnet to be used for substrates of, for example, magnetic bubble devices, the pulling up speed of the crystal is decreased with a decrease in a melt surface. In the stage when the melt decreases, the solid- liquid boundary where growh takes place actually is near the melt surface; therefore the boundary is in the position deep in the crucible. The wall in this time has probably the effect of a heat shield or an after-heater for the crystal and the melt surface. Therefore, the temp. gradient near the growth boundary is degraded. For example, it is predicted that the fluctuations in microscopic growth speed owing to the fluctuations in melt temp., etc. increase relatively by which the introduction of defects is increased. It is considered that the decreasing of the pulling up speed is effective in decreasing the generation of solidifying heat per unit time and maintaining the temp. gradient near the boundary at an effective level. |
