Luminescence of doped nanocrystalline ZnSe
- PDF / 129,468 Bytes
- 6 Pages / 595 x 842 pts (A4) Page_size
- 22 Downloads / 245 Views
Luminescence of doped nanocrystalline ZnSe J. F. Suyver1 , S. F. Wuister, T. van der Beek, J. J. Kelly and A. Meijerink Debye Institute, Physics and Chemistry of Condensed Matter, Utrecht University, P.O. Box 80.000, 3508 TA Utrecht, The Netherlands.
ABSTRACT Luminescence of nanocrystalline ZnSe:Mn2+ and ZnSe:Cu2+ prepared via an organic chemical synthesis method are described. The spectra show distinct ZnSe, Mn2+ and Cu2+ related emissions, all of which are excited via the host lattice. The Mn2+ emission wavelength depends on the concentration of Mn2+ incorporated into the ZnSe lattice, which is attributed to the presence of Mn 2+ pair-states at higher concentrations. The ZnSe:Cu2+ luminescence was studied as a function of the crystal-size. Temperature-dependent photoluminescence spectra and photoluminescence lifetime measurements are also presented and the results are compared to those of Mn2+ and Cu2+ in bulk ZnSe. INTRODUCTION Nanocrystalline semiconductors such as CdS, CdSe and ZnS have been studied extensively [1–5] and the luminescence of nanocrystalline semiconductors with optically active ions has received considerable attention in relation to possible applications [1, 2]. A simple wet chemical synthesis is attractive for device applications since large amounts of well-defined nanocrystals (NC) can be obtained in this way [5]. Efficiently luminescing ZnS:Mn2+ nanocrystals (quantum efficiency (QE) of more than 10 %) can easily be made and are considered for application in low voltage electroluminescent devices [6, 7]. Due to the unfavourable position of the ZnS valence bandedge better results are expected for doped ZnSe nanocrystals (valence band at higher energy with respect to ZnS) [8]. Recently, two reports on the synthesis and luminescence properties of nanocrystalline ZnSe doped with a luminescent ion (Mn2+ ) have appeared [9, 10]. In this paper the preparation of nanocrystalline ZnSe particles doped with 2+ Mn or Cu2+ is discussed. The ZnSe:Cu2+ product is studied as a function of particle size. Photoluminescence (PL) emission and excitation spectra are presented and discussed. Temperature-dependent luminescence and luminescence lifetime measurements are also reported and compared to results obtained for the luminescence in bulk ZnSe. EXPERIMENTAL The synthesis route that was used to prepare the doped ZnSe nanocrystals is a variation of the TOP/TOPO synthesis [9, 11, 12] and was performed in the protective dry-nitrogen atmosphere of a glovebox. A 45 ml sample of hexadecylamine (HDA) was heated to 310o C. Either a variable amount of 1
Corresponding author. Tel.: +31 − 30 − 253 2214; Fax: +31 − 30 − 253 2403; E-mail: [email protected]
G4.8.1
manganese cyclohexanebuterate powder or 4.8 mg of Cu(CH 3 COO)2 was dissolved in 12 ml of tri-n-octylphosphine (TOP). To this mixture 3 ml 1 M TOPSe (prepared by dissolving Se-powder in TOP) was added. After stirring, 0.32 g di-ethylzinc was added. This solution was shaken and then added to the hot HDA. In the case of ZnSe:Mn2+ , the nanocrystals were grown
Data Loading...
