First-principles study of phosphorus diffusion in silicon: Interstitial- and vacancy-mediated diffusion mechanisms

Abstract

A vacancy-mediated diffusion mechanism has been assumed in traditional models of P diffusion in Si. However, recent experiments have suggested that for intrinsic P diffusion in Si, the interstitial-assisted diffusion mechanism dominates. Here, we describe first-principles calculations of P diffusion in Si performed to study interstitial- and vacancy-mediated diffusion mechanisms. Special care is taken with regard to structural minimization, charge state effects and corrections. We calculated the defect formation energies and migration barriers for the various competing P–interstitial diffusion mechanisms, as well as P–vacancy diffusion energetics in different charge states. For P–interstitial diffusion, we find overall diffusion activation energies of 3.1–3.5 eV for neutral and +1 charge states, in close agreement with experiments at intrinsic conditions. For P–vacancy diffusion, our calculation is in agreement with previous calculations in the neutral case, but suggests that only P+V= plays a role in the heavily doped n region while the interstitial mechanisms may dominate in near-intrinsic regions.

Phosphorous clustering in germanium-rich silicon germanium

“…The simplest cluster considered is the PV pair. In Si this cluster was predicted to be bound by −1.23 eV in excellent agreement with previous DFT (−1.15 eV) [26] and experimental studies (−1.04 eV) [27]. In Si 1 Ge 63 the PV pair (with Si first nearest neighbour with respect to the P) is more bound compared to the equivalent pair in Ge but only by −0.04 eV.…”

Cs diffusion in SiC high-energy grain boundaries

“…The values ranged from -2.68 to 8.15 eV, with a standard deviation of 3.40 eV. The Cs, which is an impurity with a relatively larger size than those studied in the similar amorphous systems 46,47,51,[60][61][62][63] , turned out to be highly stable as interstitials in the a-SiC. The high stability of Cs defects vs. bulk is possibly due to the large relaxations available to the a-SiC system, analogous to the observation of Ag defects in the HEGB 24 , although the detailed mechanism of stabilizing Cs interstitials in a-SiC was not explicitly investigated here.…”

Sensitivity of CoSi2 precipitation in silicon to extra-low dopant concentrations. II. First-principles calculations

“…First of all, let us summarize what is known about phosphorus interstitials (PIs). The detailed first-principles analysis of PI in silicon 9 suggests that most energetically favorable configuration of electrically neutral phosphorus interstitial in intrinsic silicon is an asymmetric h110i dumbbell, consisting of phosphorus and silicon atoms. The transformation of PI into silicon self-interstitial and substitutional phosphorus (both in neutral charge states) requires the energy E b PI % 1.2 eV.…”