Growth of Tungsten Single Crystals from the Vapor State by Chemical Transport Reaction

Abstract

Fundamental researches by van Arkel [1] and Schafer [2] have been used with the molecular-kinetic theory due to Stranski and Kaischew [3] and the kinetic theory due to Frank [4] and Chernov [5] on equilibrium shapes of surfaces in defining techniques for growing metals from the vapor state by means of chemical reactions. The theoretical researches on growth forms relate mainly to one-component systems (growth from simple vapors), which differ considerably from the multicomponent systems used with chemical reactions. Morphological observations have been made on cubic body-centered refractory metals such as tungsten and molybdenum by pyrolysis of the halides [6–9], and these indicate that the equilibrium forms calculated for multicomponent systems are those that actually occur, namely {110}, {100}, {211}, and {111}. Theoretical analysis also predicts the following observed relationship between the growth rates: v₍₁₁₁₎ > v₍₂₁₁₎ > v₍₁₀₀₎ > v ₍₁₁₀₎.