| 摘要 |
Single crystals are conveniently produced by directional solidification of a liquid body under a pressurized atmosphere and, preferably, under a liquid encapsulating layer to minimize loss due to volatilization. Such fabrication entails a concern with internal stress in a grown crystal in the interest, e.g., of minimization of breakage of wafers cut from a crystal. According to the invention, minimization of stress is accomplished by means of a post-growth annealing step during which pressure is reduced substantially and, in particular, preferably to a pressure which does not exceed 50 percent of a pressure at which a constituent of the liquid body volatilizes. The method may be applied for producing single crystals of semiconductor materials as may be used as device substrates. In particular, the method is beneficial, e.g., for producing high-quality doped or undoped InP, GaP, and GaAs single crystals. |
