Đang chuẩn bị liên kết để tải về tài liệu:
A study of orange photoluminescence in cubic nanocrystals ZnS:Mn2

In our study, we have prepared nano-sized ZnS and ZnS:Mn2 powders using the co-precipitation method. We investigated the effect of the Mn2 doping concentration; and we are focusing on attempting to obtain a strong orange emission of this material. It has been observed that ZnS nanopowder of 1.0 at. Mn2+ has maximal PL emission at 590 nm. | JOURNAL OF SCIENCE OF HNUE Mathematical and Physical Sci. 2012 Vol. 57 No. 7 pp. 51-59 This paper is available online at http stdb.hnue.edu.vn A STUDY OF ORANGE PHOTOLUMINESCENCE IN CUBIC NANOCRYSTALS ZnS Mn2 Nguyen Minh Thuy Nguyen Hong Quan Nguyen Manh Nghia Nguyen Thi Van Anh Tran Minh Thi and Le Thi Hong Hai1 Faculty of Physics Hanoi National University of Education 1 Faculty of Chemistry Hanoi National University of Education Abstract. Pure ZnS and Mn2 -doped ZnS nanocrystals were synthesized using the co-precipitation method. ZnS Mn2 samples were produced by changing the V Ti ratio from 0.0 at. to 4.5 at. . The ZnS and low doped ZnS Mn2 samples are single phase with sphalerite cubic crystal structure. The average particle size is about 3 - 5 nm. The optical absorption spectra of ZnS sample are blue shifted compared to that from the bulk material reflecting a nano-size effect. The absorption edge of the ZnS Mn2 samples shifts to long wavelength with increasing Mn2 content. The photoluminescence intensity of ZnS Mn2 samples at 588 nm reached a maximum of 1.0 at. Mn2 . The high Mn doping samples show a red shift in PL peak position and the PL band becomes more broad. The calculated density of states DOS by density functional theory DFT shows that the Mn2 doping can make Mn-3d states in the band gap which are close to the top of the valence band. The calculated result of optical absorption also indicated this trend the absorption edge shifted to lower energy which is in good agreement with experimental results. Keywords Semiconductors photoluminescence absorption nanocrystals emission. 1. Introduction Zinc sulphide ZnS is an important II-VI semiconductor material with a wide direct band gap of 3.65 eV in bulk. It has potential applications in optoelectronic Received February 2 2011. Accepted Aipril 26 2012. Physics Subject Classification 62 44 07 01. Contact Nguyen Minh Thuy e-mail address thuynm@hnue.edu.vn 51 N.M. Thuy N.H. Quan N.M. Nghia N.T.V. Anh T.M. Thi