Miniband Formation in GaN/AlN Constant-Total-Effective-Radius Multi-shell Quantum Dots

We study the procedure of miniband formation in GaN/AlN constant-total-effective-radius multi-shell quantum dots (CTER-MSQDs) by calculating the subband energies. We find a different behavior of the miniband widths and miniband gaps when the number of wells changes. It is shown that with increasing the inner quantum dot radius R_in, the number of minigaps decreases; with increasing the outer quantum dot radius R_out, the number of minigaps increases. We show that in the CTER-MSQDs systems, two kinds of minigaps exist: in the type (i) ones, minigaps increase monotonically when the number of wells increases while in the type (ii) ones, with increasing the number of wells, some of minigaps create, increase, at a critical number of wells decrease and finally vanish. Thus tuning of the minigaps and miniband widths in the CTER-MSQDs systems by using the number of wells, inner and outer quantum dot radii R_in and R_out is now possible.