Exciton in wurtzite GaN/AlxGa1−xN coupled quantum dots

Based on effective-mass approximation, we present a three-dimensional study of the exciton in GaN/AlxGa1−xN vertically coupled quantum dots (QDs) by a variational approach. The strong built-in electric field due to the piezoelectricity and spontaneous polarization is considered. The relationship between exciton states and structural parameters of wurtzite GaN/AlxGa1−xN coupled QDs is studied in detail. Our numerical results show that the strong built-in electric field in the GaN/AlxGa1−xN strained coupled QDs leads to a marked reduction of the effective band gap of GaN QDs. The exciton binding energy, the QD transition energy and the electron-hole recombination rate are reduced if barrier thickness LAlGaN is increased. The sizes of QDs have a significant influence on the exciton state and interband optical transitions in coupled QDs.