Atomic and Electronic Structures of $\mathrm{GaN}/\mathrm{ZnO}$ Alloys

A new model Hamiltonian is developed to describe the ab initio energy differences of the nonisovalent alloy configurations based on the semiconductor electron counting rule. Monte Carlo simulations using this Hamiltonian show strong short range order of the $\mathrm{GaN}/\mathrm{ZnO}$ alloy, which has significant effects on its electronic structure. We also predict further reduction of the band gap by increasing the synthesis temperature.

Figure 1

Energy comparison between our models and the DFT energies (in eV/atom) for unrelaxed case (a), relaxed case (b), and two parameter form (c). Red crosses: small supercell configurations. Black filled symbols: the random configuration (triangle) and MC snapshots at 300 K (square) and 1100 K (circle) of 1280-atom supercell. Blue lines: the exact curve.

Figure 2

Snapshots of the 300 K (a) and 1100 K (b) MC simulation runs, and a randomly generated configuration (c). Zn: silver gray balls. O: red balls. Ga and N atoms are not shown.

Figure 3

Zn-O pair correlation functions of the 300 K (red) MC, 1100 K (blue) MC, and randomly generated configurations (black).

Figure 4

VBM and CBM charge density isosurfaces of the 300 K MC snapshot (a) and (b), 1100 K MC snapshot (c) and (d), and the randomly generated configuration (e) and (f). The isosurfaces contain 80% of the electron or hole charges.

Figure 5

Plots of the density of states of the 300 K MC snapshot (a), 1100 K MC snapshot (b), and the randomly generated configuration (c). $y$ axis is in arbitrary unit. The vertical arrows indicate the CBM and VBM states.