G. Janita Christobel and C.K. Mahadevan

ABSTRACT

The physical properties of two semiconductor quantum dots like ZnO and ZnS are found to get modified significantly when they are mixed with each other or doped with a transition metal element. With an aim of discovering new useful quantum dots, in the present study, we have prepared Mn2+ doped ZnSxO1-x nanocomposite quantum dots (x = 0.0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1.0) by a simple solvothermal method using a domestic microwave oven. Powder X-ray diffraction, scanning electron microscopic and energy dispersive X-ray absorption spectroscopic analyses were carried out to characterise the prepared quantum dots chemically and structurally. UV-Vis-NIR absorption, photoluminescence (PL) and photoconductivity measurements have been carried out to understand the influence of Mn2+ doping on the optical properties of ZnSxO1-x quantum dots. Results obtained indicate significant changes in the optical properties like absorption edge wavelength, PL yield and photoconductivity. All the nanocrystals (quantum dots) prepared in the present study are found to have their absorption edge wavelengths within the UV region, exhibit five prominent peaks (observed at around 400, 440,480, 490 and 530 nm) in the PL spectra and possess positive photoconductivity. Keywords: Quantum dots, Doped ZnSxO1-x nanocrystals, Solvothermal method, Optical properties.