Investigation on manganese-doped ZnSe QDs prepared from self-assembled template of reverse micelle

• Published in: Journal of luminescence Vol. 130; no. 8; pp. 1504 - 1509
• Main Authors: QI QIU, HECKLER, Tracy, JUN WANG, MEI, Bing C, MOUNTZIARIS, T. J
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 01.08.2010
• Subjects: Annealing; Block copolymers; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Crystal defects; Doping; Exact sciences and technology; Manganese; Nanocrystals; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Physics; Quantum dots; Semiconductors; Zinc selenides; Diluted magnetic semiconductor; Crystal defects; Annealing; Quantum dot; Quantum dots; Doping; Photoluminescence; Zinc selenides; Manganese additions; Self-assembled layers; Surface diffusion; Time resolved spectra; Semimagnetic semiconductors; Template method; Valence; Chemical synthesis; Reverse micelle; Nanocrystal; Nanomaterial synthesis
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2010.03.020

Compound semiconductor nanocrystals (quantum dots, QDs) of manganese-doped zinc selenide (ZnMnSe) were prepared at room temperature in a reverse micelle template consisting of poly (ethylene)-poly (propylene)-poly (ethylene) (PEO-PPO-PEO) block copolymer, p-xylene, and water. The nanocrystals showed a distinct photoluminescence (PL) peak of Mn super(2+) at the wavelength of 585 nm. Based on a gradual increase in the PL intensity from Mn relative to ZnSe, a three-stage surface diffusion process was proposed for this room temperature doping process with an initial surface adsorption and subsequent lattice incorporation until saturation of the dopant. This slow diffusion is unique and cannot be easily observed in the regular hot-injection method. QDs of larger size require higher annealing temperature. Consequently, room temperature synthesis may provide insufficient energy to anneal QDs of larger size and result in more defects in crystals. Accordingly, a decrease in PL intensity was observed for QDs with larger crystal sizes owing to more defects in those QDs. Complete doping of manganese ion into ZnSe QDs is much faster for QDs of smaller sizes. Furthermore, the overall PL intensity of the ZnMnSe nanocrystals increased significantly due to surface stabilization by the surrounding PEO-PPO-PEO block copolymer. Moreover, the PL at 585 nm was also observed for ZnMnSe prepared with different Mn valence state. This method has the potential to reveal the diffusion mechanism experimentally upon further investigation.