The polar reference QD. The growth direction  is highlighted.
The nonpolar reference QD. The growth direction is highlighted.
Polarization potential for shear piezoelectric constants in cases A and B for a polar (left) and a nonpolar (right) grown QD.
Polarization potential for the cases A and B plotted along  direction in a polar (top) and a nonpolar (bottom) grown QD for the original system geometries. The upper and lower edge of the QD are marked with vertical lines. For the polar QD, the  axis crosses the wetting layer (dashed vertical line).
Charge density of the first three electron and hole states in a polar QD for case A (outer surface: 90%, inner surface: 50%).
Charge density of the first three electron and hole states in a nonpolar QD for case A (outer surface: 90%, inner surface: 50%).
Polarization potential in a nonpolar QD plotted along  direction for different cell sizes along growth direction . The piezoelectric constants are those in case A. Vertical lines indicate the QD boundaries.
Overlap matrix element between electron ground state and the hole states , , and (top) and correspondingly for the hole ground state and the electron states , , and (bottom) as a function of characteristic dimensions of the nonpolar and the polar QD. For the polar QD, the overlap behaves antiproportional to the QD size.
Second excited electron state for the original nonpolar dot (left) and for a dot with dimensions reduced to 60% of the original size (right).
Material parameters for wurtzite GaN and AlN. Effective masses, the ’s, , and are taken from Ref. 25. , , and are taken from Ref. 26. All other parameters are taken from Ref. 27.
Overlap between different pairs of electron and hole states for the positive values of (case A, top), and negative (case B, bottom) of a polar QD.
Overlap between different pairs of electron and hole states for the positive values of (case A, top), and negative (case B, bottom) of a nonpolar QD. Note that these elements are four orders of magnitude smaller than those of polar QDs.
Charge carrier overlap in a nonpolar QD with 60% of its original dimensions.
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