Comparison of P, N and B additions during CVD diamond deposition

Using the her-filament CVD method, the influences of phosphorus. nitrogen and boron additions on the growth mechanism of diamond films were investigated using phosphine, molecular nitrogen and triethylboron additions. The limits of diamond growth were investigated, revealing those domains in which the P, N, and B additions caused transitions from sp(3) to sp(2) or amorphous structures. Comparisons of the deposition results with thermodynamic equilibrium calculations suggest that activated species (i.e. HCP, HCN, reap. BH2) induce a transition from faceted to unfaceted morphology. The observed changes of growth rate, morphology and crystallinity can be attributed either to surface or to gas phase reactions, and also to a reduction of the carbon supersaturation and defect-induced growth. It is shown that these transitions occur at concentrations that are similar for all three elements. The understanding of the mechanisms influencing the diamond growth and the incorporation of the elements P, N and B are important for doping experiments using these elements to produce semiconductive diamond. (C) 1999 Elsevier Science S.A. All rights reserved.