Formation and annealing behavior of prominent point defects in MeV ion implanted n-type epitaxial Si

摘要

Samples of epitaxially grown n-type Si have been implanted with low doses (<1 × 10~9cm~(-2)) of He, C, Si, and I ions using energies from 2.75 to 48 MeV. Deep level transient spectroscopy (DLTS) analysis of the implanted samples reveals a stronger signal for the signature of the singly negative charge state of the divacancy (V_2(-/0)) as compared to that of the doubly negative charge state of the divacancy (V_2(=/-)). Isochronal annealing for 20min ranging from 150 to 400 C results in a gradual decrease in the DLTS peak amplitude of the V_2(-/0) signature, accompanied by an increase in the peak amplitudes of both the vacancy oxygen pair (VO) and the V_2(=/-) levels, as well as an increase in the carrier capture rates for the levels. A model based on local compensation of charge carriers from individual ion tracks is proposed in order to explain the results, involving two fractions of V_2: (1) V_2 centers localized in regions with high defect density around the ion track (V_2~(dense)) and (2) V_2 centers located in regions with a low defect density (V_2~(dilute)).