Strain-confinement mechanism in mesoscopic quantum disks based on piezoelectric materials

A theoretical study of the effect of inhomogeneous strain in piezoelectric materials is presented. It is shown that for deformation potentials opposite to strain-induced piezoelectric potentials, electrons and holes can drift in opposite directions, both in the in-plane and growth directions. The resultant potential will dramatically affect the confinement of carriers in mesoscopic quantum structures. In this case, states spatially separated in the in-plane direction can be formed, giving rise to unusual optical properties. The proposed model allows for the interpretation of experimental results obtained for (Al,Ga)N∕GaN nanocolumnar structures, namely, the dependence of the luminescence intensity on the well thickness, an unusual spectral line broadening, and long lifetime contributions. This model aims to provide design rules to enhance the radiative efficiency in this type of structure.