SURFACE-ENERGY-INDUCED MASS-TRANSPORT PHENOMENON IN ANNEALING OF ETCHED COMPOUND SEMICONDUCTOR STRUCTURES - THEORETICAL MODELING AND EXPERIMENTAL CONFIRMATION

A comprehensive model of the mass-transport phenomenon at the surface of compound semiconductors has been developed and experimentally confirmed. In the model, the effect of surface curvature on thermal decomposition and the resulting diffusion and regrowth has been formulated, and a differential equation has been derived that describes the temporal evolution of any (spatially) slowly varying surface profile during mass transport. The model predicts an exponential decay of sinusoidal profiles with a fourth power of spatial wavelength dependence, and a grading of single mesa steps with a fourth root of time dependence. Good agreement with the model has been obtained in a systematic experimental study employing etched structures in InP. This study yields the low value of 1.5 eV for the activation energy of the mass-transport process in InP.