Photoemission spectromicroscopy studies on epitaxial lateral overgrowth GaN surfaces

Photoemission spectromicroscopy is employed to investigate the inhomogeneit ies of surface electronic structures of epitaxial lateral overgrowth GaN ma terial. The image, acquired on a clean surface, shows the surface morpholog y and agrees with the atomic force microscopy image. The dominant contrast mechanism is attributed to the angular dependence of the quantum yield for regions at different angles. Energy distribution curves localized to a subm icron region for the Ga 3d core level demonstrate that growth-front areas h ave different Fermi level pinning behavior compared with window areas and o vergrowth regions. The sample exposed to atomic hydrogen shows the same Fer mi level position for all areas of the surface. Photoemission spectromicros copy reveals island formation when about 10 monolayers of Mg is deposited o n the surface. (C) 1999 American Vacuum Society. [S0734-211X(99)04404-2].