Defect centers in oxygen-deficient rf-sputtered SiO2 films. II. Thermoluminescence

Abstract

Thermoluminescent (TL) glow curves of rf-sputtered SiO2 films deposited on silicon have been measured and correlated with two new defect centers detected by electron spin resonance (ESR) of the films, the HX and HY centers. As-sputtered films have low optical absorption and ESR absorption is dominated by the HY center. TL intensity is low after x irradiation. Annealing at 400°C in hydrogen, or at 550°C in nitrogen or oxygen, converts the HY center to the HX centers. TL intensity increases with annealing and goes through a maximum after annealing at 550°C in hydrogen or 650°C in nitrogen or oxygen. A characteristic TL glow curve pattern is associated with the HX centers. Trapping centers with energies of 0.74, 0.96, 1.04, and 1.20 eV are found. The complexity of TL glow curves is due primarily to variations in s, the frequency factor, rather than to a range of trap energies. It is proposed that trapping centers are associated with oxygen vacancies, and with Si–H bonds, in oxygen-deficient SiO2 films, while the recombination center is associated with bonding oxygens.