Abstract
The physical reason behind the much more rapid short-term annealing progress in the presence of electrons in P-type silicon irradiated by pulse neutrons is investigated. Continuum equations coupled with defect reactions are used for the numerical simulation on the temporary evolutions of defects at different electron injection ratios. It is indicated that electron injections can significantly accelerate the creations of boron and carbon interstitials, but may have little influence on the creation of the vacancy-oxygen complex. The calculations on the relative concentrations of interstitials and vacancies in different charge states via the electron injection ratio show that more and more interstitials in the doubly positive charge state change into neutral ones, and neutral vacancies are always dominant with an increase in the electron concentration. The thermal diffusion coefficient of neutral interstitials is much larger than the ones of interstitials in other charge states. As a consequence, normal ionization enhanced diffusion for interstitials in the presence of electrons can significantly accelerate the short-term annealing progress in P-type silicon. Ionization enhanced diffusion coefficients for interstitials due to athermal diffusion are further estimated using the Bourgoin mechanism, and results indicate that the diffusion coefficients of positively charged interstitials are improved by several orders of magnitude when compared to their corresponding thermal diffusion coefficients. However, the production of boron and carbon interstitials is only accelerated by about one order of magnitude, which would be ascribed into such large thermal diffusion coefficients of neutral interstitials.
Highlights
When energetic particles are incident on semiconductor materials, a portion of their energy deposits into ionization and the remainder deposits into atomic displacements
The temporary evolutions of V, I, VO, BI, and CI at the four different injection ratios were simulated with the consideration of normal ionization enhanced diffusion (Fig. 1)
A numerical simulation on the temporary evolutions of defects in P-type silicon irradiated by pulse neutrons was presented
Summary
When energetic particles are incident on semiconductor materials, a portion of their energy deposits into ionization and the remainder deposits into atomic displacements. Sandia National Laboratories developed a computer code Charon to simulate a silicon semiconductor device at the carrier-concentration level, including the transport of the numerous defect complexes created by neutron radiation at the short time scales and high fluence levels.. Keiter et al coupled a localized defect reaction model, a carrier model, and an integration term with a normal environment transistor model to develop a physics-based compact model of transient neutron damage.. The speculation given by McMurray and Messenger in 19819 was that the much more rapid annealing process in the presence of electrons was due to the much higher diffusion constant of vacancies in the charged state compared to the one in the neutral state This speculation is the lack of validation. Various investigations indicated that the mobility of the same defects may increase significantly when a concentration of electrons, of holes, or of electron-hole pairs is present in the crystal, which is due to the ionization enhanced diffusion (IED) in essence. Based on the numerical simulation presented in this paper, we connect the dependence of the short-term annealing process on injection levels with the IED
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