Factors determining the diameter of silicon carbide whiskers prepared by chemical vapor deposition

Since the whisker diameter is one of the important parameters for determining the characteristics of whisker-related systems, an understanding of the factors that affect its size is of great value for whisker preparation. In this study, chemical vapor deposition (CVD) of silicon carbide (SiC) whiskers using a gas mixture of methyltrichlorosilane and hydrogen has been conducted in a hot-wall reactor on graphite plates coated with Ni as a liquid-forming agent. The deposited SiC whiskers are then characterized by scanning electron microscopy (SEM) to determine their nucleation and growth behavior. Experimental results show that the diameter of SiC whiskers is determined by both the vapor-liquid-solid (VLS) mechanism and vapor-solid (VS) radial deposition, where the former is affected by the area of the solid-liquid interface from which the crystal precipitates and the latter by the thickening kinetics of vapor-deposited SiC on the lateral face. However, a comparison of the two factors indicates that an appropriate choice of the diameter of Liquid droplets for VLS whisker growth is more effective than radial VS deposition for obtaining whiskers of desired diameters. (C) 1998 Elsevier Science S.A. All rights reserved.