THE EFFECT OF TEMPERATURE ON STEP MOTION - (101) ADP FACE

In-situ Michelson interferometry was applied to study the (101) ADP face in the temperature (T) interval 29-67-degrees-C. The slopes of the growth hillock on one and the same dislocation source were independent of T. The surface diffusion model is valid for all the temperatures studied. The effective activation energy for step propagation was 65 kJ/mol for T < 40-degrees-C and 47 kJ/mol for T > 40-degrees-C. This is explained by the splitting up of nonelementary steps, existing at low T to give unitary height steps at higher T. Thus the free energy of this surface structure phase transition is DELTA-G = 18 kJ/mol. The anisotropy of the growth features is connected to the crystal structure through the "jump" distance in different directions. The activation energy for adsorption of the ADP particles on the surface is determined as E(ad) = 35 kJ/mol.