Photophysics of resonantly and non-resonantly excited erbium doped Ge nanowires

摘要

We have fabricated Er doped germanium nanowires of different diameters by pulsed laser deposition and chemical methods. Er induced photoluminescence emission due to the intra-4f ~4I _(13/2) ~4I _(15/2) transition of Er energy levels at 1.53νm has been achieved at room temperature using both resonant (980nm) and non-resonant (325nm) excitation of Er ions. The observed 1.53νm photoluminescence signal upon non-resonant 325nm excitation is attributed to the Ge related oxygen deficiency centers surrounding the Ge core. For direct excitation, the infrared photoluminescence characteristics have been studied as a function of Er concentration, photon flux, and diameter of the nanowires. The Er related emission signal is found to be enhanced with increase in Er concentration, pump flux of 980nm, and the nanowire diameter. The time resolved characteristics of the Er induced emission peak have been studied as a function of the pump flux as well as the diameter of the Ge nanowires.