Hydrogen-defect complexes formed by neutron irradiation of hydrogenated silicon observed by optical absorption measurement

Neutron-irradiation-induced defects in hydrogenated Si were investigated by detecting optical absorption due to their complexes with hydrogen. Specimens were doped with hydrogen by heating in H2 gas at 1300 °C followed by quenching in water. They were then irradiated with neutrons. The optical absorption spectra were measured at about 5 K with a Fourier transform infrared spectrometer. We investigated the dopant dependence and the annealing behaviors of H–interstitial (I) and H–vacancy (V) complexes. From the dopant dependence, we classified the peaks observed as I-related complexes or V-related complexes. In the annealing experiment, we observed numerous peaks after annealing above 300 °C in the region from 1940 to 2040 cm−1, whereas no such peaks were observed in the case of electron irradiation. This result shows that agglomerations of I and of V form more easily in neutron-irradiated Si than in electron-irradiated Si because of higher local concentrations of V and I in neutron-irradiated specimens.