Abstract
To realize the kilogram using the X-ray crystal density method, <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">28</sup> Si crystals grown by the floating zone method were employed. Samples cut from two <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">28</sup> Si crystals, the AVO28 crystal (Si28-10Pr11 crystal) and the Si28-23Pr11 crystal, were analyzed by means of an electron paramagnetic resonance (EPR) spectroscopy. The samples were prepared by mirror polishing and subsequent etching using tetramethylammonium hydroxide (TMAH) solution. TMAH etching eliminates signals from the mechanically damaged surface layers of amorphous silicon and allows for the observation of small signals from vacancy defects in bulk crystals. In the study, the signal level of the vacancy defects was below the detection limit of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1 \times 10^{12}$ </tex-math></inline-formula> cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-3}$ </tex-math></inline-formula> , and the amount of vacancy correction required to realize the kilogram was estimated to be 0.00(23) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{g}$ </tex-math></inline-formula> for both <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">28</sup> Si crystals. Therefore, it was concluded that the 39(21) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{g}$ </tex-math></inline-formula> inconsistency between the kilogram realizations achieved using the two <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">28</sup> Si crystals reported thus far cannot be explained by the existence of vacancy defects that are EPR active in the dark or under illumination.
Highlights
T HE kilogram is the base unit of mass in the International System of Units, and it has been defined by fixing the value of the Planck constant h as 6.626 070 15 × 10−34 J s [1]
Gebauer et al [5] applied positron annihilation lifetime spectroscopy (PALS) to a silicon crystal grown by the floating zone method and found that the vacancy concentration in the crystal was in the range from 1 × 1014 to 4 × 1014 cm−3 by measuring more than 5 × 106 counts at a temperature ranging from 20 to 300 K
The g factor of positively charged single-vacancy defect V + in a silicon crystal is in the range of 1.9989–2.0087, and its electron paramagnetic resonance (EPR) signal appears at a magnetic field given by the resonance condition depending on the microwave frequency
Summary
T HE kilogram is the base unit of mass in the International System of Units, and it has been defined by fixing the value of the Planck constant h as 6.626 070 15 × 10−34 J s [1]. Gebauer et al [5] applied positron annihilation lifetime spectroscopy (PALS) to a silicon crystal grown by the floating zone method and found that the vacancy concentration in the crystal was in the range from 1 × 1014 to 4 × 1014 cm−3 by measuring more than 5 × 106 counts at a temperature ranging from 20 to 300 K. It has been estimated that the Avogadro constant determined using the Si28-23Pr11 crystal (produced in 2015) is smaller than that determined with the AVO28 crystal (Si28-10Pr11 crystal, produced from 2004 to 2007) by 3.9 (2.1)×10−8 in terms of relative value [7] This corresponds to a discrepancy of 39(21) μg for the realization of the kilogram. This article is an extension of the proceedings paper presented at the 2020 Conference on Precision Electromagnetic Measurements (CPEM) [8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: IEEE Transactions on Instrumentation and Measurement
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
