Properties of Point Defects in Silicon: New Results after a Long-Time Debate

Abstract

The contributions of vacancies and self-interstitials to silicon (Si) self-diffusion are a matter of debate since many years. These native defects are involved in dopant diffusion and the formation of defect clusters and thus influence many processes that take place during Si single crystal growth and the fabrication of silicon based electronic devices. Considering their relevance it is remarkable that present data about the properties of native point defects in Si are still limited and controversy. This work reports recent results on the properties of native point defects in silicon deduced from self-diffusion experiments below 850°C. The temperature dependence of silicon self-diffusion is accurately described by contributions due to vacancies and self-interstitials assuming temperature dependent vacancy properties. The concept of vacancies whose thermodynamic properties change with temperature solves the inconsistency between self-and dopant diffusion in Si but further experiments are required to verify this concept and to prove its relevance for other material systems.

Study of the spatial distribution of minority carrier diffusion length in epiplanar detector structures

“…The generation rate of electron−hole pairs caused by an incident monochromatic radiation of l wavelength perpen− dicular to the p−n junction plane of the photodiode as a func− tion of the distance from the junction plane (x = 0) (neglect− ing the space−charge region) is expressed by the following equation [3][4][5] …”

“…Influence of native defects generated during a manufacturing process on the recombination parameters of the material is still controver− sial as clearly highlighted in Ref. 3 and requires further investigation and verification. In this article we first show a subtle spatial distribution of minority carrier diffusion length in high resistivity (>1 kW cm) epitaxy layers condi− tioned by spatial distribution of punctual defects in vacan− cies−oxygen complex formed during epitaxial growth with the MOCVD method.…”

Moment tensor potentials as a promising tool to study diffusion processes

“…Their diffusion properties are relatively well-established compared to vacancies, since extremely precise measurements of self-diffusivities are required in the latter case. Discrepancies between estimations of vacancy contribution to self-diffusion [34,35,36] indicate that this task is very challenging from the experimental point of view, see discussion in [36] for details. Therefore, an application of MTP to this problem could be of interest.…”

Electron and Proton Irradiation of Silicon

“…Bracht et al (2003) determined a value of 1.8 AE 0.5 eV from radiation enhanced self-diffusion experiments at temperatures between 780 and 872°C using 2-MeV proton irradiations for various times and proton fluxes, and Ranki and Saarinen (2004) determined a value of 1.3 AE 0.4 eV from positron-annihilation experiments of thermal vacancies generated at high temperature in highly As-and P-doped Si. In a recent review of self-diffusion studies in silicon by means of isotopically enriched silicon, Bracht et al (2014) found that the temperature dependence of self-diffusion is most consistently described with temperature-dependent vacancy formation and migration enthalpies, and they find the best description with a vacancy-migration energy varying from 0.5 eV at 700°C to 0.8 eV at 1400°C. We note that the low temperature value is not very different from the cryogenic value found by Watkins (1986).…”