Effects of built-in fields on the optical gain in a CdO/ZnO quantum dot with the Smorodinsky–Winternitz potential

Abstract

Exciton energy, with and without the inclusion of built-in internal fields, as a function of inner dot radius is investigated in a CdO/ZnO quantum dot with the Smorodinsky–Winternitz potential. The internal fields are owing to spontaneous and piezoelectric polarizations existing between the inner core and outer shell materials in the heterostructure. The dielectric mismatch effect is included. Numerical computations are carried out to obtain the exciton energy employing the variational formulism within the single band effective mass approximation. The energy shift owing to spontaneous and piezoelectric polarizations is found to be 172 meV for 20 Å quantum dot radius. The oscillator strength and the radiative lifetime as a function of dot radius are found. The optical matrix elements and the corresponding gain are studied with the constant carrier density. The optical properties are investigated using density matrix method. It is found that the substantial increase of optical gain is estimated with the inclusion of built-in internal fields.