| Popis: |
Step velocities and hillock slopes on the {1 0 0} face of KDP were measured over a supersaturation range of 0 σ σ is the supersaturation. The formation of macrosteps and their evolution with distance from the hillock top were also observed. Hillock slope depended linearly on supersaturation and hillock geometry. The two non-equivalent sectors exhibited different slopes and step velocities. AFM shows an elementary step height of 3.7 A, or half the unit cell height, whereas previous interferometric experiments assumed the elementary step was a unit cell. Values of the step edge energy ( α ), the kinetic coefficients for the slow and fast directions ( β S and β F ), and the activation energies for slow and fast step motion ( E a,S and E a,F ) were calculated to be 24.0 erg/cm 2 , 0.071 cm/s, 0.206 cm/s, 0.26 eV/molecule, and 0.21 eV/molecule, respectively. Analysis of macrostep evolution including the dependence of step height on time and terrace width on distance were performed and compared to predictions of published models. The results do not allow us to distinguish between a shock wave model and a continuous step-doubling model. Analysis within the latter model leads to a characteristic adsorption time for impurities ( λ −1 ) of 0.0716 s. |
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