Atomic-scale study on electronic structure and emission mechanism or GaN-related semi-conductor quantum dots

The atomic and electronic structures of In D2x D2Ga D21-x D2N hexagonal quantum dots (QDs) havebeen calculated theoretically. A valence-force-field method is used for the calculation of the原子positions and strain energy in the in D2x D2Ga D21-x D2N random alloy. We analyzed thebond-length and bond-angle distribution in the alloy due to the "alloy disorder." the calculatedchange in the average Ga-N and in - n bond lengths vs. x is in good agreement with the recentexperimental data. The alloy phase stability is studied on The calculated strain energy. AnD13 tight-binding method是用于the calculation of the electronic structure of thefree-standing and GaAs-embedded QDs. The energy gap, energy level，and wavefunctions are calculated accurately as a function of the QD size. For theIn the GaN barrier （dot diameter 86.4 A, dot height 20.8 A, dot）GaN barrier thickness 21a)we calculated the energies of electron and hole levels （C1-C3 and V1-V3）respectively) near the energy gap.我们发现了三个月的水平（V1-V3） are closely spaced，while the electron levels are the ground state (C1) and the closely spaced excited state （C2）C3). The gap value E D2g D2(C1-V1) is calculated to be 2.715 eV. The electron wavefunction isalmost completely confined in the QD inside，while exhibiting atomic scale fluctuation due the “alloy disorder.”

The atomic and electronic structures of InィイD2xィエD2GaィイD21-xィエD2N hexagonal quantum dots (QDs) have been calculated theoretically. A valence-force-field method is used for the calculation of the atomic positions and strain energy in the InィイD2xィエD2GaィイD21-xィエD2N random alloy. We analyzed the bond-length and bond-angle distribution in the alloy due to the "alloy disorder." The calculated change in the average Ga-N and In-N bond lengths vs. x is in good agreement with the recent experimental data. The alloy phase stability is studied based on the calculated strain energy. An spィイD13ィエD1 tight-binding method is used for the calculation of the electronic structure of the free-standing and GaAs-embedded QDs. The energy gap, energy levels, and wavefunctions are calculated accurately as a function of the QD size. For the InィイD20.2ィエD2GaィイD20.8ィエD2N QD embedded in the GaN barrier (dot diameter 86.4 Å, dot height 20.8 Å, GaN barrier thickness 21 Å), we calculated the energies of electron and hole levels (C1-C3 and V1-V3, respectively) near the energy gap. We found that the three hole levels (V1-V3) are closely spaced, while the electron levels are the ground state (C1) and the closely spaced excited states (C2 and C3). The gap value EィイD2gィエD2(C1-V1) is calculated to be 2.715 eV. The electron wavefunction is almost completely confined in the QD inside, while exhibiting atomic scale fluctuation due the "alloy disorder."