Isotope effects and temperature-dependence studies on vibrational lifetimes of interstitial oxygen in silicon

Vibrational lifetimes of the asymmetric stretch mode (1136 cm−1) of oxygen in silicon are measured using pump-probe spectroscopy and calculated by ab initio theory. We find that increasing the isotope of the nearest-neighbouring silicon atom increases the lifetime of the vibration. This isotope-dependence establishes the participation of the ν1 (613 cm−1) local vibrational mode in the decay of the ν3 (1136 cm−1) mode. Temperature-dependence measurements show the low-energy ν2 (29 cm−1) mode governs the repopulation rates for the ground state. We also analyze the temperature-dependence of transitions of excited states of the ν2 vibration.