Charge-carrier recombination in silicon irradiated with γ-rays of different energies

Abstract

Comparative experiments are made to study the nonequilibrium charge‐carrier recombination in silicon irradiated with γ‐rays of 50Co and of the bremsstrahlung spectrum of electrons with maximum energy 100 MeV. n‐ and p‐Si crystals with ϱ = 10 to 1000 Ωcm grown by Czochralski and vacuum float‐zone techniques are used. The temperature and injection dependences of nonequilibrium charge‐carrier lifetimes measured by a phase method are analyzed. It is found that when irradiating with γ‐rays of 60Co a great number of recombination centers are produced which are mainly complexes of irradiation‐generated vacancies and interstitials with dopants (phosphorus, boron) and technological (oxygen, carbon) impurities. As distinct from this, the dominant recombination centres in silicon irradiated with γ‐rays of the bremsstrahlung spectrum are divacancies involved in defect clusters, surrounded by the potential barrier Ψ for the majority charge carriers. The parameters of recombination centres (energy level spectrum, annealing temperatures, charge‐carrier capture coefficients) in crystals studied under γ‐irradiation are determined. The peculiarities in the charge‐carrier recombination processes due to the localization of recombination centres in defect clusters generated by photonuclear reaction products are discussed.

Lifetime Control in Irradiated and Annealed Cz n‐Si: Role of Divacancy‐Oxygen Defects

“…We also note that the influence of other radiation‐induced defects (in particular V 2 and VP) on τ degradation in 60 Co γ‐irradiated Cz n‐Si is negligible . However, in the case of V 2 , this effect becomes noticeable in Cz n‐Si after high‐energy (≥6 MeV) electron irradiation as a result of a decrease in the ratio .…”

“…First, DLTS and Laplace DLTS studies of the kinetics of V 2 annealing and V 2 O formation in DOFZ and Cz n-Si show that the transformation of V 2 to V 2 O occurs with an almost one-to-one proportionality. [5][6][7][8] Second, the peak-like change of Δτ À1 (Figure 5 and 6) and the change in the V 2 O concentration in Cz n-Si are clearly correlated in the annealing range of 180-380 C. [7] In an earlier work, from the analysis of the temperature dependence of τ in γ-irradiated and annealed Cz n-Si (n 0 ¼ 7 Â 10 13 cm À3 ), it was found that the acceptor with level E c -0.45 eV is responsible for τ degradation in the range %200-300 C. [18] It is noted that the level of this defect is practically the same as the level of V 2 O(À/0).…”

“…We also note that the influence of other radiation-induced defects (in particular V 2 and VP) on τ degradation in 60 Co γ-irradiated Cz n-Si is negligible. [16][17][18][19] However, in the case of V 2 , this effect becomes noticeable in Cz n-Si after high-energy (≥6 MeV) electron irradiation as a result of a decrease in the ratio η VO =η V 2 . [14,[20][21][22] For example, the ratio η VO =η V 2 % 80 for 60 Co γ-irradiation and η VO =η V 2 % 4-5 for 3.5 MeV electron irradiation.…”

Carrier Lifetime in 60Co Gamma and 1 MeV Electron‐Irradiated Tin‐Doped n‐Type Czochralski Silicon: Conditions for Improving Radiation Hardness

“…The VO (acceptor level of E c ‐0.17 eV) is the dominant recombination center at room temperature in 60 Co γ‐irradiated Cz n‐Si with P doping levels 10 13 –10 17 cm −3 . [ 30–33 ] Then the total change of carrier lifetime is expressed aswhere τ VO is carrier lifetime associated with VO defect.…”

Influence of Divacancy-Oxygen Defects on Recombination Properties of n-Si Subjected to Irradiation and Subsequent Annealing

“…5 in work [11]). In work [21] on the basis of the temperature dependences of in -irradiated and then annealed high-resistive Cz -Si specimens ( 0 = 7 × 10 13 cm −3 ), it was shown that the degradation is driven by an acceptor with a level of c − 0.45 eV (supposedly, this is C O -V 2 ). However, the recent DLTS researches do not support this hypothesis.…”