Specific Surface Area of Evaporated Aluminum

Abstract

The variations in the specific surface area of evaporated aluminum due to substrate temperature, film thickness, and angle of incidence have been determined experimentally. Increasing the substrate temperature from 0° to 100°C decreases the specific surface area by a factor as large as 9. Increasing the film thickness from 3000 to 12 000Å increases the specific surface area by a factor as large as 17. The specific surface area increases with increasing angle of incidence and has been observed to change in the range of 1.0 to 25.2. Atomistic models for the growth of rough films from vapor are considered. One model which has been proposed in which asperities grow from islands which form during the initial stages of condensation is rejected on the basis of experiment. A second model in which asperities grow from crystallites having preferred crystallographic orientations is found to be adequate to explain the observations of this and certain other investigations.