Infrared absorption study of a DX-like hydrogen-related center in silicon

Abstract

An absorption line at 1025.5 cm −1 has been found in hydrogenated Czochralski-grown Si crystals after irradiation with fast electrons and annealing in the temperature range 300–400°C. Substitution of hydrogen by deuterium resulted in a shift of the band to 1027.9 cm −1, which clearly indicates H(D) incorporation into the defect which gives rise to the band. It is found that the line is related to a local vibrational mode (LVM) due to a DX-like center, having a shallow donor and a deep acceptor level. The LVM band is observed only when the center is in the singly negatively charged state. Transformation of the defect into the neutral state resulted in disappearance of the LVM band and appearance of several absorption lines in the range 245–325 cm −1. These lines were interpreted to be associated with ground-to-excited-state electronic transitions in an effective-mass-like shallow donor state of the defect. The structure of the center is discussed.