Exciton states and interband optical transitions in InGaN quantum dots

Within the framework of the effective-mass approximation, exciton states confined in wurtzite InxGa1−xN strained quantum dots (QDs) are investigated by means of a variational approach, including three-dimensional confinement of the electrons and holes in QDs and a strong built-in electric field effect due to the piezoelectricity and spontaneous polarization. Our results show that the strong built-in electric field gives rise to an obvious reduction of the effective band gap of QDs and leads to a remarkable electron–hole spatial separation. This effect has a significant influence on exciton states and optical properties of the QDs. The relationship between exciton states and height of QDs is studied. A comparison of the calculated and measured emission wavelengths for different InxGa1−xN QDs is given and a good agreement is obtained.