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Plotted is the discontinuity in the normal component of the polarization at an interface between GaN and . The arrow indicates the angle between the surface normal and the bulk -axis. Each curve corresponds to the indicated.
The relative stability for surfaces is shown as a function of . In the Ga-rich limit the lowest energy structure is C, which exhibits two layers of Ga in L1 and L2. This structure is shown on the right. Ga atoms are gray, and N atoms are small red spheres.
surfaces. A, B, D, and E contain successively more In atoms in layers L0, L1, and L2. Indium atoms are large green spheres, Ga atoms are gray, and N atoms are small red spheres.
Relative energies for surfaces for N-rich conditions. denotes the indium concentration in layer L0 (see Fig. 3). Indium incorporation in layer L0 is exothermic provided that . The transitions from B to C and C to D both occur near .
Shown are four surfaces. P is the Ga-N dimer terminated surface. Surfaces Q, R, and S have respectively 0, 1/2, and 1 ML incorporated in the GaN layer below the adlayer.
Energies of surfaces in N-rich conditions. Incorporation of indium becomes favorable after the transition from P to R, which occurs at . Structures Q, R, and S are shown in Fig. 5. The transition from Q to R would occur at −0.18 eV, and a transition from R to S would occur at 0.02 eV. Thus . The transition to S is prevented by the formation of In droplets.
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