Coupled electromechanical effects in wurtzite quantum dots with wetting layers in gate controlled electric fields: The multiband case

We quantify the influence of coupled electromechanical effects on the band structure calculations of wurtzite AlN/GaN quantum dots with wetting layers (WLs). Based on a strain dependent fully coupled 8-band k·p method, we computed eigenvalues and wavefunctions of electrons in quantum dots with WLs of different aspect ratios. These computed eigenvalues are compared to those obtained from the method based on decoupled 2-conduction and 6-valence bands envelope functions. Previously, such comparisons, accounting for the wetting layer, were systematically done only for models based on not more than 4-bands. In addition, we apply gate potential along z-direction to bring the conduction and valence bands closer so that we numerically estimate the influence of gate controlled electric fields on the intra-subband energy in quantum dots. Due to the non-parabolicity term in the effective mass approximation, our study shows that the intra-sub band energy (i.e., the energy difference between ground and first excited states) is smaller for electrons and larger for holes in the 8-band k·p method than those eigenvalues obtained from the decoupled 2-conduction and 6-valence bands envelope functions method. In this paper, we show that the intra-sub band energy increases in presence of piezo-electromechanical effects and externally applied gate potentials along z-direction. We numerically estimate the distribution (i.e., the probability density) of electrons and holes wavefunctions in the dots that is obtained from both the 8-band k·p method and the decoupled 2- and 6-bands envelope functions method.