Energy Gap Dependence on Mn Content in a Diluted Magnetic Quantum Dot

Positively charged donor exciton binding energy is computed as a function of quantum-dot size within the single band effective mass approximation for different Mn contents in Cd_1−xin Mn_xinTe/Cd_{1−x out}Mn_xoutTe. The exciton bound polaron is computed for 0≤x≤0.08, on the Mn mole fraction. We determine the energy gap using the mean field approximation and incorporate the exchange interaction between the carrier and the magnetic impurity. The interband emission energy is studied with the height and radius of the cylindrical quantum dot. Valence-band anisotropy is included in our theoretical model using different hole masses in different spatial directions. Spin polaronic shifts as functions of quantum-dot radius and Mn concentration are estimated using the mean field theory. It is found that (i) the energy gap depends on the Mn mole fraction, (ii) it increases linearly with an increase in Mn content, and (iii) the effect is more pronounced for a narrow dot, showing the quantum size effects. Our results are in good agreement with other recently published reports.