Optical Spectroscopy for The Growth of Nano crystals of CdSe

Abstract

There is an ever increasing interest in nanostructures in recent year’s especially inorganic semiconductor nanostructures which have a distinguishable role in fundamental studies and technical applications because of their shapes - and sizes-dependent properties and flexibleprocessing methods. Cadmium selenide (CdSe)is considered direct band gap II-VI semiconductor where the band gap favours absorption on a spacious range ofthe visible spectrum. In this research, high grade CdSe nano crystal particles were studied using optical spectroscopy in orderto understand the growthof CdSe. In order to define their properties of Nano crystals and study their relation with other parameters .CdSe nanoparticles were prepared from Cd (Se2CNMenHex)2 at 200°C in a similar way to the Bawendiroute.The particles sizeofNano crystalsCdSe and theirdistribution with time was studied bysome factors such as peak energies and delta energy gab and absorption values and constants related to CdSe material. Two methods were used to find the particles diameter size. first method using computer programming depending onexcelprograminthecalculationandthesecondmethodusinghanddrawingthatusedtomakefittingtothe analysis data.bothmethods gavevery closeresults .concluded fromthesetwomethods thatthereis adirect relation between particle size and the time .as time increase, growth in particle size occurs .and also there is an inverse relationbetween peak energy andtimeas time increasepeakenergy decrease. Structuralcharacterisation ofCdSeparticleswas investigated by using thePowderX-RayDiffraction(PXRD)wherethePXRDpatternhad appeared less well defined because of lower synthetic temperatures lead to smaller particles and increase the likelihood ofdefects.