Local structure and Er~(3+) emission from pseudo-amorphous GaN: Er thin films

摘要

We report on strong Er~(3+) luminescence in the visible and infra-red regions at room temperature in amorphous GaN:Er thin films prepared by DC magnetron co-sputtering. The intensity of the Er~(3+) luminescence at 1.535 #mu#m corresponding to ~4I_(13/2) -> ~4I_(15/2) transitions is greatly enhanced after annealing at 750 deg C. In this material GaN crystallites have formed and embedded in the continuous amorphous matrix. The crystallites are 4 to 7 nm in diameter as analyzed by high resolution transmission electron microscopy. The absorption edge, extending three orders of magnitude in absorption coefficient in the spectral range from 0.5 to 3.5 eV, is superimposed on resonant absorption bands of Er~(3+) ions. The total photoluminescence spectrum consists of well-defined Er~(3+) luminescence peaks imposed on a broad band edge luminescence from the amorphous GaN host matrix.