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摘要
Lightly-doped silicon (Si) samples of n-type conductivity have been irradiated with 2,0 MeV H+ ions at a temperature of 30K and characterized in situ by deep level transient spectroscopy (DLTS) measurements using an on-line setup. Migration of the Si mono-vacancy in its double negative charge state (V2-) starts to occur at temperatures above similar to 70K and is monitored via trapping of V2- by interstitial oxygen impurity atoms (0), leading to the growth of the prominent vacancy-oxygen (VO) center. The VO center gives rise to an acceptor level located at similar to 0,17 eV below the conduction band edge (E-c) and is readily detected by DLTS measurements. Post -irradiation isothermal anneals at temperatures in the range of 70 to 90K reveal first-order kinetics for the reaction V2- + O-i -> VO (+2e(-)) in both Czochralski-grown and Float -zone samples subjected to low fluences of H+ ions, i.e. the irradiation -induced V concentration is dilute (<= 10(13) cm(-3)), On the basis of these kinetics data and the content of 01, the diffusivity of V2- can be determined quantitatively and is found to exhibit an activation energy for migration of 0.18 eV with a pre-exponential factor of similar to 4 x 10(-3) cm(2) s(-1). The latter value evidences a simple jump process without any entropy effects for the motion of V2-. No deep level in the bandgap to be associated with V2- is observed but the results suggest that the level is situated deeper than similar to 0.19 eV below E, corroborating results reported previously in the literature,
- 出版日期2017-5-24
