TABLE OF CONTENTS Thin films grown under the conditions of low-adatom mobility (T < 0.25T M), incident particle energy less than about 1 eV, and with a unidirectional flux of impinging atoms develop a fibrous or columnar structure in which the intercolumn space is less dense than that in the intracolumn space.1 This region of lower density has been described as a "void" network,2 although the shape of the "voids" is more ribbon-like3 than "void-like". The columns or fibers abut, but not perfectly. They may be either crystalline4 or amorphous.5 It has been stated that there are five different scales of void networks and associated columns; the smaller ones are contained within the larger ones, and the size of the largest one is dependent on the film thickness.6 The angle made by the fibers with the film normal, ? is often related to the angle of incidence of the impinging atoms, ? by 2 tan ? = tan ? the tangent "law".7 However, this "rule" is not always obeyed.8 The interfiber spacing is a function of the substrate9 and the substrate temperature.10 The void network disappears above a critical temperature, T 1.1 Let us consider first the origin of the intercolumnar voids and then the relationships between processing and the void network.
Numerous computer simulations have been performed to study the phenomenon of intercolumn "void" net works.11 ,...
