Cation incorporation rate limitations in molecular-beam epitaxy - Effects of strain and surface composition

The effects of strain and surface composition on cation incorporation rates in III–V molecular‐beam epitaxy are examined for three growth systems. In initial stages of strained InAs on GaAs(001) heteroepitaxy, lattice‐mismatch strain is found to reduce the cation incorporation rate (relative to that of InAs homoepitaxy) by lowering the energy barrier associated with cation desorption. The magnitude of this energy barrier is found to depend on surface reconstruction. In unstrained InAs homoepitaxy, the energy barrier associated with In desorption is found to be 4.0 eV; this value is found to be in excellent agreement with predictions based on simple bond energy scaling arguments applied to results obtained for GaAs homoepitaxy. In unstrained growth of AlxGa1−xAs on GaAs(001), surface chemical composition is found to affect the Ga incorporation rate in a complicated manner: the presence of Al results in an increase in the Ga incorporation coefficient even though the energy barrier associated with Ga loss is...