title: X-ray absorption near edge spectroscopy with a superconducting detector for nitrogen dopants in SiC.
abstract: Fluorescence-yield X-ray absorption fine structure (FY-XAFS) is extensively used for investigating atomic-scale local structures around specific elements in functional materials. However, conventional FY-XAFS instruments frequently cannot cover trace light elements, for example dopants in wide gap semiconductors, because of insufficient energy resolution of semiconductor X-ray detectors. Here we introduce a superconducting XAFS (SC-XAFS) apparatus to measure X-ray absorption near-edge structure (XANES) of n-type dopant N atoms (4 ×10(19) cm(-3)) implanted at 500°C into 4H-SiC substrates annealed subsequently. The XANES spectra and ab initio multiple scattering calculations indicate that the N atoms almost completely substitute for the C sites, associated with a possible existence of local CN regions, in the as-implanted state. This is a reason why hot implantation is necessary for dopant activation in ion implantation. The SC-XAFS apparatus may play an important role in improving doping processes for energy-saving wide-gap semiconductors and other functional materials.
authors.affiliation: Research Institute of Instrumentation Frontier (RIIF), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan. m.ohkubo@aist.go.jp
authors.forename: M
authors.initials: M
authors.lastname: Ohkubo
authors.forename: S
authors.initials: S
authors.lastname: Shiki
authors.forename: M
authors.initials: M
authors.lastname: Ukibe
authors.forename: N
authors.initials: N
authors.lastname: Matsubayashi
authors.forename: Y
authors.initials: Y
authors.lastname: Kitajima
authors.forename: S
authors.initials: S
authors.lastname: Nagamachi