The aggregation of Fe3+ and their d-d radiative transitions in ZnSe:Fe3+ nanobelts by CVD growth.

ABSTRACT

Transition metal (TM) doped II-VI semiconductors have attracted great attention due to their luminescence and diluted magnetism. In this study, the Fe3+-doped ZnSe nanobelts (NBs) were grown by a facile CVD method. The surface morphology observed via SEM is smooth and clean and the elemental composition measured via EDS confirms that the Fe3+ ions were incorporated into ZnSe NBs successfully. The micro-Raman scattering spectra demonstrate that the as-prepared NBs have the zinc blende structure. Furthermore, the Raman spectra of the Fe3+-doped NBs were compared with those of pure and Fe2+-doped reference samples. The former with a higher signal-to-noise ratio, an enhanced 2LO mode, a stronger LO mode redshift and a larger intensity ratio of LO/TO mode as well as the lower acoustic phonon modes confirms the better crystallization and the stronger electron-phonon coupling on Fe3+-incorporation. The emission of single Fe3+ ion, assigned to the 4T1 → 6A1 transition, was observed at about 570 nm. Moreover, increasing the doping concentration of Fe3+ ions caused the formation of different Fe-Fe coupled pairs in the lattice, which emitted light at about 530-555 nm for an antiferromagnetic-coupled pair, possibly due to the stacking faults and at about 620-670 nm for a ferromagnetic-coupled pair.