Abstract
Here, we have developed a new series of quantum dots based on the incorporation of thulium, Tm, atoms as efficient dopant in the cubic CdTe crystal structure for laser diode application potential. Therefore, Cd-1 - xTmxTe (0 <= x <= 0.07) quantum dots were synthesized using s,s'phenylenebis-ethynediyl-phenylene-bisthioacetate assisted microwave approach. The measurements of X-ray diffractions implied the preservation of the cubic phase of the CdTe crystals at all Tm dopant contents. The transmission electron microscopy inspected the formation of monodisperse and self-assemble nanoparticles with mean diameter from 1.8 +/- 0.2 nm to 5.7 +/- 0.3 nm, depending on the amount of Tm incorporated in the CdTe nanocrystals. A modulation of the optical bandgap was observed because of the doping of CdTe with Tm atoms. Highly luminescent emission spectra with tunable colors were obtained. The emission spectra showed sharp intense emitted light with an enhancement of its intensity reached to seven folds compared with the un-doped CdTe crystals. An increasing of quantum yields from 31% to 94% was realized. A decrease of the Stokes shift was observed which implies the synthesis of Cd1 - x TmxTe QDs free of defects for the first time. This unique performance renders the prepared Cd1 - x TmxTe to be potential candidate for the manufacturing of laser diodes.