Thermal donors formation via isothermal annealing in magnetic Czochralski high resistivity silicon

Abstract

A quantitative study about the thermal activation of oxygen related thermal donors in high resistivity p-type magnetic Czochralski silicon has been carried out. Thermal donor formation has been performed through isothermal annealing at 430°C up to a total time of 120 min. Space charge density after each annealing step has been measured by transient current technique. The localized energy levels related to thermal double donors ͑TD͒ have been observed and studied in details by thermally stimulated currents ͑TSCs͒ in the range of 10-70 K, and activation energies E and effective cross sections have been determined for both the emissions TD 0/+ ͑E = 75± 5 meV, =4ϫ 10 −14 cm 2 ͒ and TD +/+ ͑E = 170± 5 meV, =2ϫ 10 −12 cm 2 ͒. The evolution of the space charge density caused by annealing has been unambiguously related to the activation of TDs by means of current deep level transient spectroscopy TSC, and current transients at constant temperature i͑t , T͒. Our results show that TDs compensate the initial boron doping, eventually provoking the sign inversion of the space charge density. TD's generation rate has been found to be linear with the annealing time and to depend critically on the initial interstitial oxygen concentration, in agreement with previous models developed on low resistivity silicon.

Grown-in defects limiting the bulk lifetime of p-type float-zone silicon wafers

“…Aside from oxygen, 17 the recombination activity of these impurities is not well understood, and their impact on the lifetime, even at low concentrations (<1 Â 10 16 cm À3 ), is not known. 18,19 Thus, it cannot be assumed that impurities unintentionally incorporated into a) the FZ ingot will not degrade the minority carrier lifetime to some extent, especially if they interact with other intrinsic defects within the silicon crystal. Recently, Rougieux et al have shown that nitrogen-related defects (possibly vacancy-nitrogen pairs) could be responsible for a significant reduction in s bulk observed in n-type FZ silicon, where [N] ¼ $5 Â 10 14 cm À3 .…”

Investigating thermal donors in n-type Cz silicon with carrier density imaging

“…2 They introduce two distinct energy levels, E c -0.075eV and E c -0.170eV, into the Si forbidden gap. 3 When the dopant density is below 5×10 15 cm -3 , each TD will provide two electrons and TDs are thus double donors. In this case, the TD concentration in n-type silicon can be calculated as [TDs] = (n-N D )/2 where n is the free carrier density in the as-grown silicon and N D is the donor (phosphorus) concentration.…”

Identification of a fast diffusing oxygen species in silicon based on the generation rate of thermal donors

“…The properties of oxygen are still an important issue in silicon technology and science, in particular considering oxygen transport, precipitation and formation of thermal donors (TDs) , and the phenomenon of anomalous long‐distance oxygen diffusion is worth analysing.…”