Defect Behaviour in Deuterated and Non-Deuterated n-Type Si

Abstract

Deep level transient spectroscopy (DLTS) has been performed on deuterated and non-deuterated p + -n - -n + Si-diode detectors made from oxygenated, low-doped, high-purity FZ-Si wafers. The deuterated samples were exposed todeuterium plasma at 150 °C for 2 and 4 h, respectively. All the samples were then irradiated with 6-MeV electrons to a dose of 2 x 10 1 2 cm - 2 . In the as-irradiated state the concentration of electrically active defects is the same in all groups of samples. The samples were subsequently annealed isochronally for 15 minutes at temperatures from 100 to 400 °C. No difference in the DLTS spectra is seen for the samples after annealing up to 200 °C. After annealing at 200 °C and above, however, pronounced differences in the annealing behaviour of the defects are observed. In the non-deuterated samples, the peaks of the two known divacancy levels (V 2 ) shift slightly during the annealing steps up to 300 °C. This shift is, from previous reports, ascribed to the interaction of V 2 with interstitial oxygen which results in the divacancy-oxygen centres (V 2 O). In the deuterated samples the two V 2 centres are fully annealed at 250 °C, without the transition to V 2 O. In the sample deuterated for 4 h the disappearance of the VO peak, starting during the annealing at 200 °C, coincides with the appearance of two peaks with positions at 0.17 and 0.58 eV below the conduction band, respectively.