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 according 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 interstep distance is around 150 nm. The spiral steps are well developed around the screw dislocations, while the adjacent vicinal steps lack the regularity of the spiral steps. Two-dimensional nucleation islands are also observed on the vicinal steps.