STUDIES OF LARGE-SCALE UNSTABLE GROWTH FORMED DURING GAAS(001) HOMOEPITAXY

Atomic force and scanning tunneling microscopy studies have been perfo rmed on GaAs(001) films grown by molecular beam epitaxy. Multilayered mounds are seen to evolve when the growth conditions favor island nucl eation. As the epilayer thickness is increased, these features grow in all dimensions but the angle of inclination remains approximately con stant at 1 degrees. The mounding does not occur on surfaces grown in s tep-flow. We propose that the multi-layered features are due to an uns table growth mode which relies on island nucleation and the presence o f a step edge barrier.