Ex situ investigation of the step bunching on crystal surfaces by atomic force microscopy

We are describing ex situ observation of step bunching on the surfaces of solution grown potassium dihydrogen phosphate (KDP) and sodium chlorate monocrystals. The measurement have been done with the use of Atomic Force Microscope. The use of this equipment allowed ic see directly the structure of macrosteps. Observation confirmed the existence of step pinning which is one of the proposed mechanism of step bunching. Despite of the very high resolution of AFM it was not possible to determine the nature of pinning point. The monatomic steps on KDP and sodium chlorate crystal surfaces are mainly one unit cell high what seems to be the result of the steps pairing. The origin of observed step pattern is discussed in frames of existing theories.