Excitonic properties of strained wurtzite and zinc-blende GaN/AlxGa1−xN quantum dots

By Vladimir A. Fonoberov, Alexander A. Balandin. 2003

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We investigate exciton states theoretically in strained GaN/AlN quantum dots with wurtzite (WZ) and zinc-blende (ZB) crystal structures, as well as strained WZ GaN/AlGaN quantum dots. We show that the strain field significantly modifies the conduction- and valence-band edges of GaN quantum dots. The piezoelectric field is found to govern excitonic properties of WZ GaN/AlN quantum dots, while it has a smaller effect on WZ GaN/AlGaN, and very little effect on ZB GaN/AlN quantum dots. As a result, the exciton ground state energy in WZ GaN/AlN quantum dots, with heights larger than 3 nm, exhibits a redshift with respect to the bulk WZ GaN energy gap. The radiative decay time of the redshifted transitions is large and increases almost exponentially from 6.6 ns for quantum dots with height 3 nm to 1100 ns for the quantum dots with height 4.5 nm. In WZ GaN/AlGaN quantum dots, both the radiative decay time and its increase with quantum-dot height are smaller than those in WZ GaN/AlN quantum dots. On the other han...

Subfields: Biomedical Engineering, Condensed Matter Physics, Mechanics of Materials

View Paper: https://www.semanticscholar.org/paper/71bc2fdca5d975d1ff1b2c2104a3ebb3480cbb3b