Enhancement of spontaneous emission and material gain from CdSe/CdS quantum dot

This study looks at the material gain and enhanced spontaneous emission of CdSe(1-x)S(x)/ZnS and CdSe(1-x)S(x)/ZnO quantum dot (QD) structures. (remove dot) cadmium selenide (CdSe) QDs, cadmium sulfide (CdS) wetting layer (WL), zinc oxide (ZnO) and zinc sulfide (ZnS) as a barrier layers were investigated to achieve QDs semiconductor with active region (B). The energy levels and band alignment between layers are predicted using the quantum disk model. Gain is an estimation for the transverse electric (TE) and magnetic (TM) modes in QDs structures, taking into consideration the momentum matrix element. The mole-fraction (x) and contributions of the barriers (ZnO and ZnS) material in enhanced gain and spontaneous emission were investigated in this manuscript. When ZnS is used as a barrier material, the spontaneous emission is found to be 11.75×10^19 (eV.sec.cm^3 )^(-1) at x~0.69 and wavelength 324 nm, and the material gain has maximum values of order 5.671×10^4 cm^(-2) for TM and 3.743×10^7for TE modes, respectively. Whenever the barrier is changed to ZnO, the results are different; at x~0.438 and wavelength 365 nm, the spontaneous emission becomes 2.965×10^19 (eV.sec.cm^3 )^(-1) and the gain has maximum values of order 2.118×10^4 cm^(-2) for TM and 1.242×10^5 cm^(-2)for TE mode.