Pressure dependent optical gain in Type-II PbSe/PbS core /shell quantum dots

Abstract

Pressure induced nonlinear optical properties of Type-II lead based core/shell quantum dot heterostructure are investigated. The pressure dependent exciton binding energies are obtained with the increase of shell thickness for various inner core radii. The exciton interaction energies in a PbSe/PbS core/shell quantum dot inner core radii are found in the presence of hydrostatic pressure using variational method within the single band effective mass approximation. The threshold current density with the hydrostatic pressure and inner dot radii in a PbSe/PbS dot with the constant shell width is obtained. The pressure dependence on peak optical gain with the current density in a PbSe/PbS core/shell quantum dot with the fixed carrier density is found. The pressure related optical gain with the photon energy in a PbSe/PbS core/shell quantum dot is also obtained. The results show that the threshold current density increases by 20% when the pressure increases from 0 GPa to 4 GPa for 20 Å quantum dot radius whereas 16% of increase in threshold current density is observed for 50 Å quantum dot radius for the same increase of pressure values. The peak of the optical gain is observed to increase nonlinearly with the applied hydrostatic pressure and 12% of optical gain is enhanced for every 2 GPa pressure value. The results will be useful for some potential applications in near infrared light sources.