Effect of Ga content on crystal shape in micro-channel selective-area MOVPE of InGaAs on Si

We investigated the dependence of the growth mode on the Ga content in micro-channel selective-area MOVPE of InGaAs on Si(111) substrates by changing the partial pressure of a Ga source. The Ga content in the crystal was affected by the initial nucleation and the shape of InGaAs islands after growth. In the growth of InAs, a single columnar nucleus was generated in each open window and a hexagonal column was eventually grown. The content of the initial nuclei of InGaAs were close to InAs. As the partial pressure of a Ga source was increased, the number of nuclei in a growth area increased, their shape became rounded, and a slight amount of Ga was incorporated into the nuclei. The InGaAs islands showed enhanced lateral growth as the partial pressure of a Ga source was increased and incoherent growth without specific crystallographic planes became apparent at a high Ga content. The InGaAs islands that grew in the lateral direction had an inhomogeneous Ga content with a higher Ga content at the peripheral region. It appears that incorporation of Ga suppresses coherent growth of In(Ga)As in the vertical direction and enhances lateral growth, although high Ga content can induce incoherent growth. (C) 2008 Elsevier B.V. All rights reserved.