Effect of the Er-Si interatomic distance on the Er3+ luminescence in silicon-rich silicon oxide thin films

The photoluminescence (PL) intensity of Er-doped silicon monoxide thin films obtained by coevaporation of silicon monoxide and Er is studied for different deposition and annealing atmosphere compositions. All samples exhibit a luminescence peak at 1.54 mu m assigned to the radiative deexcitation of Er3+. PL intensity is highest when nitrogen atoms are incorporated in the layer during deposition. Extended x-ray absorption fine structure spectroscopy evidences that the local order around the erbium ion is modified in the presence of nitrogen. In particular, the shorter the Er-Si interatomic distance is, the higher the Er3+ PL intensity is.