Diffused Nitrogen-Related Deep Level in N-Type Silicon

Abstract

Deep levels are found in n-type silicon that is annealed in N2 and quenched to room temperature. The energy level and capture cross section of the deep levels are estimated to be about E c-0.42 eV and of the order of 10-17 cm2, respectively. The charge state of the deep levels is determined to be acceptor type by measuring the temperature dependence of the Schottky junction capacitance made in the specimen with the deep levels. The depth profile of the deep level density is found to correspond to that of the complementary error function, and the diffusion coefficient calculated from the profile is in good agreement with that of nitrogen in silicon. It is assumed that generation of deep levels is due to the formation of nitrogen-vacancy complexes, because quenching to room temperature and several hours' storage after quenching are required to form the deep levels. In order to confirm this assumption, we attempted to control the deep level density by changing the vacancy concentration. Oxidation of the specimen surface and formation of oxygen precipitates in silicon are known to decrease the vacancy concentration, since they supply excess interstitials from the oxide and silicon interface. Experimental results clearly show that the deep level density observed in these specimens is very low.

Vibrational modes and electronic properties of nitrogen defects in silicon

“…An acceptor level labeled T1 at E c Ϫ0.42 eV and concentration ϳ10 15 cm Ϫ3 was found when n-type silicon, into which nitrogen had been diffused at around 700°C, was quenched. 45 This was assigned to a vacancy-dinitrogen complex, although there was no direct evidence for the number of nitrogen atoms in the center. In the material that was quenched ͑1 s͒ from the nitrogen in-diffusion temperature (750-850°C) to room temperature and subsequently annealed at room temperature or 100°C for a few hours, the depth profile of T1 followed that of the nitrogen profile and was activated with an energy of 2.65 eV: a value close to the diffusion barrier of (N i -N i ).…”

Scanning transmission electron microscope analysis of amorphous-Si insertion layers prepared by catalytic chemical vapor deposition, causing low surface recombination velocities on crystalline silicon wafers

“…[9][10][11] These defect complexes are believed to form deep levels and act as carrier traps. 12,13 The results of the present study, hence, suggest that N-related defect complexes may play a major role in surface recombination of photoexcited carriers in c-Si wafers passivated by SiN x layers.…”

Crystal Growth of Silicon for Solar Cells

“…Few experimental data are available about nitrogen diffusivity in solid and liquid silicon in the literature [136][137][138][139][140][141][142]. The liquid diffusivities reported by Mukerji and Biswas [142] were several orders of magnitude lower than the solid 236 K. Tang et al [136][137][138][139][140][141][142] diffusivities.…”