Growth of crystals from the gas phase. Part II. Diffusional limitations and interfacial stability in crystal growth by dissociative sublimation, with an inert third gas present

The quantitative treatment of interfacial stability in crystal growth from the vapour phase, presented in a previous paper, has been extended to cover (1) large temperature differences between source and seed, (2) arbitrary temperature profiles, and (3) an inert third species in the gas phase. The effect on the growth rate and critical growth rate of altering the temperature profile has been investigated and found to be small if the slope at the growing interface is above about 10 K cm^–1. The influence of small quantities of inert gas on the temperature difference corresponding to the critical growth rate is shown to provide a useful stabilising effect against unavoidable temperature fluctuations. At the same time, the partial pressure ratio α of the active components becomes a less sensitive function of the distance along the growth capsule. The treatment is general; however, the familiar case of cadmium sulphide is included as an illustration and for comparison with our previous results.