Surface reconstruction of GaP(001) for various surface stoichiometries

The surface stoichiometry and reconstruction of GaP (001) are investigated by means of reflection high-energy electron diffraction and surface photo-absorption. The experiments were carried out using a solid-source molecular beam epitaxy system with a cracker cell as a P source. When the amount of Ga supplied to the surface is over 2 monolayer (ML), the 2 x 4 reconstruction corresponding to the P-stabilized surface is observed in spite of the existence of excess Ga on the surface. The change of surface reconstruction may be interpreted as follows: the surface is a Ga-terminated structure up to 2 ML of Ga supply, then Ga atoms move to some nonperiodic sites such as Ga droplets.