Microscopic evidence for role of oxygen in luminescence of Er3+ ions in Si: Two-color and pump-probe spectroscopy

Influence of oxygen on optical activity and thermal stability of the 1.5 mu m emission of Er3+ ions in Si is well documented. Here we support this predominantly phenomenological notion with microscopic evidence. Using two-color and pump-probe spectroscopy with a free-electron laser we establish a direct link between the 1.5 mu m emission from Er3+ ions and the 9 mu m vibrational band of interstitial oxygen in Si. We show that: i) intensity of the 1.5 mu m emission quenches when the 9 mu m oxygen vibration is resonantly excited, and ii) the lifetime of the 9 mu m vibrational band is affected by Er presence. Both findings evidence microscopic relation of interstitial oxygen and Er and their close proximity in Si matrix.