Motlan, Guanghua Zhu, K. Drozdowicz-Tomsia, K. McBean, M.R. Phillips, E.M. Goldys
ZnS nanocrystals (NCs) capped with tetramethylammonium (TMAH) were synthesized from ZnCl2 · 2H2O and thiourea using a wet chemical process. Further treatments of the nanocrystals such as aging, and annealing have been conducted to examine the stability of the grown samples. The X-ray diffraction spectra show that the crystal has a zinc blende structure with particle size of about 2 nm. The evidence of nanocrystalline character is also clear in the UV-Vis absorption that shows an excitonic peak at about 236 nm (5.2 eV) arising from band edge transitions. A photoluminescence emission peak centered at about 450 nm (2.7 eV) is attributed to transitions between shallow donors and Zn+ vacancies. Both absorption and photoluminescence spectra show that sample aging does not affect the characteristics of the sample, possibly due to protection by TMAH capping. Annealing at 700 °C and 900 °C results in the red shift of the photoluminescence. © 2006.
Physics Department, Division of Information and Communication Sciences, Macquarie University, North Ryde, NSW 2109, Australia; Microstructural Analysis, University Technology of Sydney, Sydney, NSW 2007, Australia; College of Public Health, Southeast University, Nanjing, 210009, China; Physics Department, Faculty of Mathematics and Natural Science, State University of Medan, 20221, Indonesia
