| 摘要 |
<PICT:0793071/III/1> Single crystals are produced by deposition from the vapour phase by vaporizing the material to be deposited, exposing a substrate to the vapour, controlling the degree of supersaturation of the vapour by the adjustment of the temperature of the vapour according to the equation: <FORM:0793071/III/1> (where a is the ratio of the partial pressure of the vapour to the equilibrium partial pressure of the vapour at the deposition temperature, a is the interlayer spacing of the material, p is the density of the material, o is the surface free energy of the material, k is Boltzmann's constant, R is the molar gas constant, B is equal to 1020 seconds-1, </>pN is the surface nucleation rate for the material, and T is the deposition temperature in degrees Kelvin) and maintaining the deposition temperature of the substrate below that of the vapour so that two-dimensional nucleation of the material on the substrate is presented, whereby single, rod-like crystals are formed on the substrate. Material 8 (Fig. 2) to be crystallized is placed in a container 5, which is evacuated at 9, the container then being heated by two furnaces 6 and 7. The temperature of the furnace 7 is the deposition temperature T in the equation above, and is lower than the temperature of the furnace 6 which vaporizes the material. The temperature difference is adjusted so that the proper degree of supersaturation of the vaporized material is maintained, and rod-like single crystals 10 are deposited on the upper walls of the container 5. Examples of materials crystallized are cadmium, zinc, silver and cadmium sulphide, and the corresponding temperatures and values for a are given.
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