THERMODYNAMIC THEORY FOR PREFERRED ORIENTATION IN CARBON AND CUBIC BN

The applications of thermodynamic theory to preferred orientations bas ed on minimization of the Gibbs free energy is discussed in order to a ddress the difficulties raised in recent work by Cardinale et al. [G. F. Cardinale et al., J. Vac. Sci. Technol. A 15, 196 (1997)]. We find that the preferred orientation of the cubic form of BN with the [111] direction lying in the stress plane is correctly described by the theo ry provided that the term linear in stress is included. We also descri be how the predictions of this theory for the hexagonal forms of BN an d for glassy carbon under compressive stress conditions are reconciled with measurement by allowing for reductions in the elastic constant s (44) caused by imperfections. (C) 1998 American Vacuum Society. [S0734 -2101(98)06304-0].