Interface supersaturation dependence of step velocity in liquid-phase epitaxy of InP

Abstract

By employing microchannel epitaxy (MCE), it became possible to reduce the dislocation density in liquid-phase epitaxy (LPE) of InP, so that steps supplied from only one screw dislocation can cover whole surface of MCE island. This enabled us to measure interstep distance by AFM and to calculate interface supersaturation even in metallic solution with the help of the formula given by Cabrera and Levine. From the interstep distance, the step velocity was calculated by employing the macroscopic vertical growth velocity. It was found that the step velocity increases linearly with the increase of the interface supersaturation, and the slope of the curve, which gives a step kinetic coefficient of the growth, increases with the increase of the growth temperature. From the Arrhenius plot of the kinetic coefficient, the activation energy of step advance was found as E=32.8 kJ/mol. A critical value of the interface supersaturation σ c, below which steps do not move, has also been found to exist. It was also found that σ c decreases with the increase of the growth temperature. The presence of σ c probably means that step advance is stopped by the impurity pinning effect.