Hydrogenated Radiation Defects in Silicon: Isotopic Effect of Hydrogen and Deuterium

The isotopic effect of hydrogen and deuterium on hydrogenation of radiation defects introduced in n-type float zone and Czochralski silicon by irradiation with high-energy alphas was investigated. Silicon diodes were first irradiated with 2.4 MeV alphas to a fluence of 1x10¹⁰ cm^-2 and then hydrogen or deuterium was introduced by rf plasma treatment at 250°C. Reactions of hydrogen and deuterium with radiation defects were monitored by deep-level transient spectroscopy during subsequent isochronal annealing at temperatures ranging from 100 to 400ºC. Results show that hydrogen rf plasma effectively neutralizes majority of vacancy related radiation defects created by alphas in both materials. In contrast with it, neutralization by deuterium plasma is substantially weaker. Disappearing of vacancy related defect levels due to hydrogen (deuterium) treatment is accompanied by introduction of two dominant deep levels at E_C-0.309 eV and E_C-0.365 eV. While hydrogenation significantly accelerates annealing of radiation defects especially in Czochralski material, deuteration has weaker effect and gives rise to new defect levels during annealing.