Condensation of metal and semiconductor vapors during nozzle expansion

Abstract

We consider the homogeneous nucleation and growth of metal and semiconductor clusters resulting from an adiabatic cooling during the expansion of the vapor through a crucible nozzle. It is argued that although the surface tension of most metals and semiconductors is high, the nucleation barrier and critical cluster size are still comparable to that of the gases because of the high vaporization temperature. The nucleation rate is evaluated for a variety of metals and semiconductors based on the classical nucleation theory. Prediction of the lower limit of the Ag pressure for which the vapor attains an appreciable nucleation rate agrees well with a recent cluster beam experiment.