Lasers, Optics & Photonics

Biography

Biography: Hye Mi Cho

Abstract

Recently, quantum dots have been investigated as promising optoelectronic materials because of its unique optoelectronic properties and high stability compared with bulk material by quantum confi nement eff ect. Quantum dots have been studied to solve the limitations of commotional optoelectronic device. For example, the luminescence wavelength can be shift ed to a visible wavelength range with quantum dots. Th erefore, quantum dots optoelectronics can be applied into not only biochemical applications but also light emitting diodes (LEDs), laser and fl uorescent biological label. The composite semiconductor nanocrystals such as CdS, CdSe and ZnSe have been studied for photoluminescent quantum dots materials. Above all, CdSe is advantageous materials because it has bright luminescence in the visible range of the optical spectrum and easily fabricable in well-dispersed nano-sized crystals. The properties of CdSe quantum dots core such as reaction temperature, concentrations and time can be varied using the synthetic parameters. The most of cases, CdSe quantum dots were synthesized by a colloidal process with phosphine (PH3) precursor such as TOP, TOPO and TBP. However, conventional colloidal methods with PH3 were suitable, hazardous and pollutive. In this study, quantum dots are successfully synthesized using phosphine-free colloidal method under various conditions is confi rmed to control surface properties. In order to evaluate the size dependence of CdSe crystal, synthesis temperatures were changed from 2400C to 3000C and precursor ratio (Cd:Se) was controlled. The optical properties of the synthesized CdSe quantum dots were confi rmed using photoluminescence (PL). Th e microstructure and phase developments were measured by transmission electron microscopy (TEM) and X-ray diff ractometer (XRD) respectively.