Observation and theory of the V-O-H-2 complex in silicon

The interaction of hydrogen with radiation-induced defects (RD's) in Czochr alski-grown silicon crystals has been studied by infrared-absorption spectr oscopy and ab initio modeling. Hydrogen and/or deuterium was introduced int o the crystals by indiffusion from H-2 (D-2) gas at 1200-1300 degrees C. Th e samples were subsequently irradiated with fast electrons (E = 2-4 MeV) an d annealed in the temperature range of 100-600 degrees C. The centers produ ced by the irradiation were the same in both the untreated and treated case s, namely the A-center, Ci-Oi complex, and divacancy. A heat treatment of t he H-treated samples resulted in the enhanced loss of these centers and the formation of centers containing hydrogen. The disappearance of the A cente rs in the temperature range of 100-150 degrees C is correlated with the app earance of three local vibrational modes (LVM's) at 943.5, 2126.4, and 2151 .5 cm(-1). The isotopic shifts of these lines were obtained from measuremen ts on the samples doped with hydrogen and deuterium. The lines are identifi ed as related to stretching vibrational modes of a complex that consists of one oxygen and two hydrogen atoms sharing a vacancy site (V-O-H-2 complex) . Ab initio calculations are used to explore the structures and properties of this defect. The origin of other LVM bands, which were observed upon ann ealing, is discussed.