Local vibrational mode bands due to a DX-like hydrogen-related center in silicon

Abstract

An absorption line at 1025.5 cm−1 has been observed in hydrogenated Czochralski-grown silicon crystals after irradiation with fast electrons and following annealing in the temperature range of 300–400 °C. The line was found to be related to a local vibrational mode (LVM) due to a DX-like hydrogen-related center, having a shallow donor and a deep acceptor electronic level. This LVM band was observed when the center was in the singly negatively charged state. Transformation of the defect into the neutral charge state due to photoionization resulted in disappearance of the LVM line and the appearance of several absorption lines in the range of 250–325 cm−1. These lines were interpreted earlier to be associated with ground-to-excited-state electronic transitions in an effective-mass-like shallow donor state of the center. Substitution of hydrogen by deuterium resulted in a shift of the LVM band to 1027.9 cm−1 that unambiguously indicates hydrogen incorporation into the defect. The structure of the center which gives rise to the observed absorption bands is discussed.