Studies of Radiation Damage in Degenerate Silicon Irradiated at Low Temperatures

Abstract

Pulled (Czochralski) and float-zone w-type (NC,NF) and ^>-type (PC,PF) degenerate Si samples were irradiated in the 10-140°K temperature range, using 1-MeV electrons, and were studied by observing changes which occur in the dc conductivity <r and Hall coefficient RH as a result of bombardment and various thermal treatments. For PC and PF, carrier removal rates remained practically constant at 0.7 and 1.1 cm -1 , respectively, for irradiation temperatures between 7 and 90°K. In contrast, NC and NF removal rates increased nearly exponentially with irradiation temperature above approximately 60°K, while below « 60°K they were exceedingly small (<0.02 cm"" 1 ). Radiation-induced recovery due to 350-keV electrons was observed in ntype Si. This effect exhibits a strange temperature dependence, being quite efficient below a characteristic temperature and very inefficient above that temperature. The kinetics of radiation annealing at afgiven temperature is a superposition of two first-order processes. The metastable-pair model is compared with one based on a mobile interstitial. Defects introduced into degenerate Si at low temperatures show high resistance to thermal annealing, in contrast to the behavior of nondegenerate material. Isochronal annealing runs indicate that complete recovery occurs only around 1000°K. Some of the recovery stages are tentatively identified with specific defect structures previously reported in the literature. Detailed results of isothermal annealing experiments in the first recovery stage of ^>-type Si (295-265°K) are given.

Defect-Enhanced Charge Transfer by Ion-Solid Interactions in SiC using Large-ScaleAb InitioMolecular Dynamics Simulations

“…Defect diffusion mechanisms and corresponding migration energies also depend strongly on defect charge states, particularly in covalent and ionic materials [5,6]. It has been shown that the charge state of preexisting interstitials can be changed under low-energy electron irradiation, leading to radiation-enhanced annealing that has been observed in Si, Ge, diamond, and GaAs [7][8][9][10]. Although radiation-enhanced annealing is a well-known process in the physics and materials communities, the theoretical interpretation remains controversial [11,12].…”

Similarities and distinctions of defect production by fast electron and proton irradiation: Moderately doped silicon and silicon carbide of n-type

“…However, this can be assessed based on the data obtained for heavily doped n Si. For heavily doped n Si with n ≈ 10 19 cm -3 , in which the average distance between V group impurity atoms is only 30 Å and the trapping of vacancies at V group impurity atoms can be greatly enhanced, the removal rate of charge carriers η c under irradiation with 1 MeV electrons turned out to be 1.1 cm -1 [27]. Therefore, the fraction f FP of sep arated primary defects is equal to 25%, in the belief that the nature of dominating complexes remains the same.…”