Quantum dots of zinc sulphide | |
| Author | Ghosh, Subir Chandra |
| Call Number | AIT Thesis no. ME-03-09 |
| Subject(s) | Quantum dots Zinc sulphide |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Advanced Technologies |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. ME-03-09 |
| Abstract | Luminescent II-VI semiconductor nanocrystals have attracted a lot of attention in the past two decades due to their unique properties and potential applications in electronics, lighting industry, military and medical fields. The optical properties of the nanocrystals can be tailored by controlling crystallite size and/or doping with luminescent ionic centers. Because of stability, tunablility and higher efficiency, luminescent nanomaterials or otherwise known as quantum dots or simply Q-dots, are becoming a potential candidate to replace all the existing phosphors and drawing more attention of researchers at present. Colloidal Q-dots of zinc sulphide doped with manganese has been synthesized in aqueous medium using sodium polyphosphate as the stabilizing agent. It has been observed that particle agglomeration depends very strongly on the amount of stabilizing agent used during synthesis. XRD measurement reveals that the quantum dots of zinc sulphide has Zinc Blende structure having planes at. { 111 }, {220} and {311} with crystallite size to be around 2.02 nm as calculated by Debye-Scherrer formula. The presence of phosphate group in the powder form of ZnS:Mn2+ has been confirmed by FTIR spectroscopy of the samples. The nanoparticles have an optical absorption edge at around 285 nm and under UV exposure, it glows with an orange colour and it is visible even in day light illumination. Quantum dots of ZnS:Mn2+ passivated with chitosan has also been synthesized with a view to finding applications in biology. The luminescent quantum dots functionalized with biocompatible chitosan has been attached to the anionic cell wall of Bacillus cereous which assemble themselves like a honey comb structure. It has been observed that the particles self assemble themselves along the walls of bacteria depicting the structure as formed by the bacteria- an example of bio-assisted self assembly. This exciting result may pave the way of finding a cost effective alternative of using nanocrystals for bioapplications instead of organic fluorophores presently used. |
| Year | 2003 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. ME-03-09 |
| Type | Thesis |
| School | School of Advanced Technologies (SAT) |
| Department | Department of Industrial Systems Engineering (DISE) |
| Academic Program/FoS | Microelectronics (ME) |
| Chairperson(s) | Dutta, Joydeep; |
| Examination Committee(s) | Rakshit, Sudip Kumar;Chanchana Thanachayanont;Dha, Sumi N.; |
| Scholarship Donor(s) | Asian Institute of Technology Fellowship; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2003 |