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Diffusion of Gold into Heavily Boron-Doped Silicon
Published online by Cambridge University Press: 15 February 2011
Abstract
Diffusion of Au into dislocation-free and highly dislocated Si with high B-background doping levels has been investigated with the aid of neutron activation analysis in conjunction with mechanical sectioning. The high B-doping level causes extrinsic conditions, i.e., the hole concentration exceeds the intrinsic carrier concentration even at diffusion temperatures between 900°C and 1100°C. All profiles are accurately described on the basis of the kick-out diffusion model and a mechanism which takes into account segregation of Au at dislocations. Our analysis provides solubility data of Au in Si and effective diffusion coefficients related to interstitial Au and Si self-interstitials I. The dependence of these quantities on the B-background doping level is well described by the Fermi-level effect. This analysis supports singly positively charged states in p-type Si of Au on interstitial (Aui) and substitutional (Aus) sites and of Si self-interstitials. Successful fitting of additionally requires an acceptor level of Aus. The electrical properties deduced for Aui, Aus and I are summarized in Table 2. Au profiles in highly dislocated Si obtained especially after diffusion at 900° C give evidence of Au trapped at dislocations. From our preliminary experimental results we determine an enthalpy difference of 2.7 eV between Au on substitutional sites and Au captured at dislocations.
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- Copyright © Materials Research Society 1997
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