Near-infrared luminescence of Nd3+ and Tm3+ ions doped ZnO nanocrystals.

Intense near-infrared luminescence of Nd(3+) and Tm(3+) ions in the region of 860-1550 nm were achieved in 10-15 nm wurtzite ZnO nanocrystals fabricated by a facile sol-gel process. The optical properties of Nd(3+) and Tm(3+) ions were investigated by using the steady-state and time-resolved laser spectroscopy. Due to the well-ordered crystal-field surroundings experienced by Nd(3+) and Tm(3+) ions, sharp and well resolved emission lines of Nd(3+) and Tm(3+) ions were identified at 4-300 K. Time-resolved luminescence and decay behaviors of the (4)F(3/2)-->(4)I(11/2) transition of Nd(3+) ions reveal the existence of multiple Nd(3+) sites in ZnO nanocrystals.