| 摘要 |
PURPOSE:To improve the yield and reproducibility in the preparation of the titled single crystal containing volatile component by the direct-synthesis direct-pulling process or the liquid-encapsulated pulling process, by detecting the resistance of the molten liquid with one or more pairs of electrodes, and controlling the pulling conditions of the crystal according to the detected resistance. CONSTITUTION:In the preparation of semi-insulating GaAs single crystal by the direct- synthesis direct-pulling process, Ga and As are charged in the crucible 2 in a pressure vessel 1 using larger amount of As than the stoichiometric value, and are covered with a sealant 3 such as B2O3. The crucible is heated with the heater 5 to form a GaAs compound and melt the compound. For example, W-electrode pair 7 are put into a pair of cells 6 made of thermally decomposed boron nitride and filled with molten Ga as a nonvolatile electrically conductive liquid, and the cells are inserted into the crucible 2 at a definite depth interposing a gap between the bottom of the crucible. The change in the electrical current between the electrodes is detected by the detector 9, and when the current is decreased below a preset level, the seed crystal 10 is pulled up, and when the current is increased above a preset level, the pulling of the seed crystal is stopped to obtain the grown crystal 11. |
