High Purity Isotopically Enriched²⁹Si and³⁰Si Single Crystals: Isotope Separation, Purification, and Growth

Abstract

The phonon-assisted luminescence in AgBr: I is discussed in the framework of a conventional configuration coordinate model in which both optical and acoustic phonons are coupled to the excited electronic states. We derive the expression for the luminescence intensityusing the coherentphonon description for the displacedoscillator (excited impurity) in a consequent way. As compared to the conventional derivation we gain in simplicity and transparency of the calculation. With the formulae derived, the experimental results concerning the spectral features of the luminescence as well as their dependence on temperature are well reproduced. In particular the importance of the acoustical phonon contribution in determining the correct intensity and its temperature dependence is stressed. Furthermore the question of the interpretation of the experiments in terms of the introduced coherent phonon states is discussed.

Isotope engineering of silicon and diamond for quantum computing and sensing applications

“…These stable isotopes can be separated by centrifuging SiF 4 gas. [23,24] The first isotopically engineered silicon was produced in 1958 to characterize the electron spin resonance (ESR) of donors in silicon. [25] Since then, no results on this topic were reported until a strong interest emerged in the mid-1990s, when isotopically enriched 28 Si single crystals were employed as the standard to define the Avogadro constant.…”

“…IKZ established various Czochralski [23,33] and floating-zone [34] growth techniques to maintain the isotopic composition of the starting charge. Here various isotopes ( 28 Si, 29 Si, and 30 Si) of different enrichments were employed as starting charges as described in Ref.…”

“…[40] The isotopically enriched 28 Si chemical vapor deposition (CVD) films were grown from isotopically enriched silane ( 28 SiH 4 ) gas by the Isonics Corporation, USA, from 1998 to 2005. Because centrifuge isotope separation was performed using SiF 4 as described elsewhere 23 , the resulting isotopically enriched 28 SiF 4 was transformed to 28 SiH 4 (silane) by an electronic materials company named Voltaix. The quality of the Isonics epilayers, especially the residual impurity concentration, fluctuated significantly between the different epilayers because the company outsourced the CVD growth to other companies.…”

Host isotope mass effects on the hyperfine interaction of group-V donors in silicon

“…The samples D, H, and I were Czochralskigrown while the rest were float-zone grown, using the methods described in Ref. 24 26 were studied as well. Pulsed ENDOR experiments were performed using Bruker Elexsys580 spectrometer at X band (9.7 GHz) equipped with a helium-flow cryostat.…”

Electron spin resonance identification di-carbon-related centers in irradiated silicon

“…Furthermore, it was impossible to do this for the hyperfine interaction with the 29 Si nuclei having low (4.7%) abundance. Once can increase the 29 Si concentration through isotope engineering [10][11][12] to make the hyperfine 13 C satellites. However, too much abundance of 29 Si may lead to broadening of the main peak which can overlap with the hyperfine 13 C satellites.…”