| 摘要 |
1,270,065. Mixed crystals. INTERNATIONAL BUSINESS MACHINES CORP. 21 Sept., 1970 [23 Sept., 1969], No. 44809/70. Heading BIG. Mixed crystals are grown from a melt containing one component on to a seed of the other, the melt being supplied with the second component by contacting it with the solid form of this component at another point. The melt has the composition from which a solid of the desired mole fractions of its components will be precipitated on freezing, and is maintained at this composition by equilibriating it at constant temperature with the second component source. The temperature at the point of contact between the liquid and the seed is controlled to permit freezing, and hence crystal growth to occur. By varying the equilibrium temperature, it is possible to prepare mixed crystals whose composition varies either gradually or stepwise in the growth direction. In the embodiment described a mixed crystal of GaP and InP is prepared. The lower melting compound, InP, is sandwiched between two layers of Gap, the InP melted and equilibrated with the GaP, the lower interface cooled to permit crystal growth and the ensemble slowly lowered through a cooled zone so that growth occurs upwards. Additional phosphorus vapour is supplied to keep the vapour pressure equal to or above the dissociation pressure of the phosphorus. The process may also be used for ternary &c systems. |
