INFLUENCE OF FE3+ AND AL3+ IONS ON THE KINETICS OF STEPS ON THE (100)FACES OF KDP

The influence of iron and aluminium impurities on the dependence of th e layer growth rate versus the solution supersaturation was studied us ing the method of in situ interference microscopy. The dead zone of su persaturations was determined as well as the critical supersaturation value when the rate sharply increases with different impurity concentr ations. Analysis of decelerating action of these impurity stoppers sho ws that they are firmly adsorbed by the surface and the Cabrera-Vermil yea mechanism is at work, the question of how the stopper is trapped b y the crystal is still unanswered.