K. Jayanthi

Observation of Nd3+ visible line emission in ZnO : Nd3+ prepared by a controlled reaction in the solid state

Visible emission from ZnO is usually broadband and realizing line emission from rare earth f?f transitions in ZnO at room temperature has proven to be difficult. A controlled solid-state reaction process with different standing times to synthesize rare earth doped (Nd3+) zinc oxide (ZnO) has shown that sharp and intense line emission in the orange region (595?nm) could be realized under blue excitation, where both excitation and emission transitions occur between Nd3+ levels situated intragap in ZnO. In addition, host-to-Nd3+ energy transfer is also observed under band-to-band excitation. Incidentally, undoped ZnO synthesized by an identical process exhibits a broad green emission. Detailed characterization of the ZnO?:Nd3+ powder by x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, x-ray photoelectron spectroscopy, photoluminescence spectroscopy and time-resolved decay indicates a hexagonal phase with the presence of Nd3+ in the ZnO lattice, forming spherical particles (?200?nm) having a sharp visible emission with decay time in the microsecond range (9.60??s).

Electronic and Luminescent Characteristics of Aluminum Doped ZnO Nanocrystals

Aluminium doped ZnO (AZO) nanocrystals were prepared under different ambient conditions (argon and air) to study the effect of structural, luminescence and electronic properties. AZO nanocrystals were highly crystallized in hexagonal wurtzite phase with spherical morphology. Prominent yellow emission is observed in both the AZO samples owing to recombination between Al3+ donor levels and intrinsic acceptor centre. Both AZO samples exhibit n-type conduction with resistivity of AZO prepared in inert (argon) ambient condition showing lower resistivity compared to the one synthesized in air atmosphere.