IN-SITU STUDY OF SURFACE PHENOMENA BY REAL-TIME PHASE-SHIFT INTERFEROMETRY

Real time phase shift interferometry is applied to the observation of a growing crystal surface. Detailed profiles of a growth hillock, such as local vibrations of slopes and height differences of growth steps, are clearly distinguished on a barium nitrate crystal, together with measurements of growth rate at each location. It was found that the he ight difference of 0.92 nm was directly detectable in this interferome try, indicating that the present method is a few ten times more sensit ive than conventional two-beam interferometry, applicable to in situ s tudy, such as Michelson interferometry. It was found that: (1) Step sp acing gradually increases as a step approaches the edge of a crystal, which is inferred from the non-uniformity of surface supersaturation. (2) The observation of fluctuation of the growth rate under a constant condition was analyzed as due to the unequal separation of neighborin g dislocations which produce the perturbation of steps.