Figures

Figure 1

Contour plot of the valence-electron density for the (1x1) Ga-terminated (000) surface in the (1-210) plane. The units are in [10^-3 e/bohr^-3]. Note the clear enhancement of the charge density in the top surface layer which is characteristic for the strong Ga-Ga interaction and the metallic bonding in the surface. The plane plotted contains the [000] and the [100] directions.

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Figure 2

Examples of surface structures containing As in the first and second layer for the cubic (001) surface. The surface energies are given for Ga (left number) and N-rich (right number) conditions.

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Figure 3

Surface energies [in eV/(1x1) cell] for the (0001), the (000) and the (001) surfaces [solid, dashed, doted line] as a function of the As coverage. The energies are relative to the energy of the corresponding equilibrium surfaces for each orientation.

Figure 4

Atomic structures of the wurtzite [(0001), a)] and [(000), b)] surfaces. Large (grey) balls mark Ga atoms, small (green) balls N atoms.

Figure 5

Diffusion pathways and diffusion barriers for isolated Ga (left) and N (right) adatoms on the Ga-terminated (1x1) GaN (001) surface. A top view of the surface is shown in the center. The large balls mark the Ga atoms, the smaller the N atoms in the second layer. The diffusion path is marked as dotted line. Note that for the Ga adatom two inequivalent paths with almost degenerate barriers exist.

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© 1998 The Materials Research Society