Interband and intersubband optical transition energies in a Ga0.7In0.3N/GaN quantum dot

Abstract

Binding energies of a hydrogenic donor impurity and an exciton are investigated in a Ga0.7In0.3N/GaN parabolic quantum dot taking into consideration of spatial confinement effects and the magnetic and electric fields. The strain effects and the built-in internal fields which are related to the piezoelectricity and spontaneous polarization are inserted in the Hamiltonian of the system. Numerical calculations on electronic and optical properties are performed using variational formulism and the density matrix approach. The diamagnetic shift is obtained taking into the account the geometrical confinement effect of the dot. The magnetic and electric fields dependent interband and intraband optical transition energies are obtained in the strong and weak confinement effects. Their corresponding oscillator strengths as functions of magnetic and electric fields are investigated. The optical absorption coefficients due to intersubband and interband transitions with the photon energy are obtained. The results show that the energy shift is much influenced with the inclusion of external perturbations. Specifically, the optical absorption peak undergoes a redshift with the application of electric field whereas it suffers a blue shift when the magnetic field is applied. The results will be helpful for the experimental works on fabricating optical devices such as photodetectors and laser amplifiers using nitride based wide band gap semiconductors.