Analysis of vapor deposition processes

Abstract

A general formulation is presented for describing the net rate of vapor deposition from a molten source onto an initially cold condensing surface. In the formulation allowance is made for diffusion and molecular transport and the resultant equations are shown to reduce to the correct expression for molecular distillation at low residual pressures. In the statement of the problem allowance is also made for possible heat transfer effects when the latent heat of deposition is not dissipated rapidly enough. Under these conditions the diffusional or molecular transport problem has to be solved together with the appropriate transient heat conduction equations written for the deposit and the backing plate. The computed results were shown to agree reasonably well with previously reported measurements on vapor deposition, and the formulation given here may thus be used for identifying the various asymptotic regimes of vapor deposition processes.