Capping layer thickness and quantum dot height dependences of strain and internal field distributions in wurtzite InGaN/GaN quantum dots

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Strain and internal field distributions in wurtzite (WZ) lens-shaped InGaN/GaN quantum dots (QDs) were investigated as a function of both a QD height (dh) and a capping layer thickness (Lc). The polarization in the QD with a relatively large dh rapidly decreases with increasing Lc while that in the QD with a relatively small dh is a weak function of Lc. This is connected with the fact that the variation by Lc of the strain component, εzz, in the QD is dominant for the QD with a large dh. The potential difference affecting the spatial separation of electron and hole wavefuntions is shown to increase rapidly with increasing Lc. However, it begins to decrease when Lc is further increased. These results can be used as a design guideline for fabrication of high-efficiency QD-based optoelectronic devices.