SPIRAL GROWTH OF GAAS BY METALORGANIC VAPOR-PHASE EPITAXY

Growth spirals are observed on metalorganic vapor phase epitaxy grown GaAs surfaces by atomic force microscopy. The growth mechanism is acco rding to the classical Burton-Cabrera-Frank theory. Spirals originate from screw dislocations. Successive turns of steps are sent out by the dislocations. These steps are of monolayer height (0.28 nm) and the i nterstep distance is around 150 nm. The spiral steps are well develope d around the screw dislocations, while the adjacent vicinal steps lack the regularity of the spiral steps. Two-dimensional nucleation island s are also observed on the vicinal steps.