Diffusion coefficient of a pair of nitrogen atoms in float-zone silicon

Abstract

Outdiffusion profiles of nitrogen in silicon were measured by secondary ion mass spectrometry to determine its diffusion coefficient in a temperature range of 800–1200 °C. The total amount of the nitrogen outdiffusion agrees with the change in infrared absorption by heat treatment. The experimental results give the diffusion coefficient of nitrogen as D=2.7×103 exp(−2.8eV/kT)cm2/s. This value is five orders of magnitude larger compared with the reported expression of 0.87 exp(−3.29eV/kT)cm2/s. Nitrogen–nitrogen-pair-like molecule in crystals corresponds to the former value and substitutional nitrogen atom to the latter one. These two types of nitrogen in silicon may allow us to clarify the various effects of nitrogen such as strengthening of crystals and suppression of swirls and D-defect generation.