GROWTH AND MELTING OF THE CLEAVAGE FACE $\{10 \bar{1}1\}$ of Yb:YAl3(BO3)4 Crystal

Abstract

Yb:YAl3(BO3)4 (YbYAB) is a self-frequency-doubling laser crystal. In this paper, we report a series of atomic force microscopy (AFM) observations on the growth and melting of the cleavage face [Formula: see text] of the crystal. Both growth and nucleation rates are very fast when the flux temperature is 0.5–1.5°C below the saturation point. These fast growth and nucleation rates are related to the nonsaturated bonds on the cleavage face formed during cleaving. The growth morphologies sensitively change to spiral melting holes when the flux temperature increases by only 0.5°C above the saturation point. When the temperature increases by another 1°C, the spiral melting mechanism transforms into a two-dimensional nucleation melting mechanism. The heights of the growth or melting steps are n × unit height of the structure layer in this direction. The melting step height increases much as the temperature increases by 1°C, but the growth step height increases only a little as the temperature decreases by 1°C. The melting steps are much wider than the growth steps, which reflects the fact that the melting centers (or melting nuclei), unlike the growth nuclei, are difficult to form. The growth morphology is not reverse-symmetric to the melting morphology as the temperature variation is reverse-symmetric on the saturation point.