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 ×1019 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.

The new 6 MV multi-nuclide AMS facility at the University of Tsukuba

“…This new multipurpose tandem accelerator will see various uses, including, AMS, IBA, ion irradiation, and nuclear physics. The new system will start routine multi-nuclide AMS measurements of 10 Be, 14 Fig. 3.…”

“…The Tsukuba 6 MV AMS system is expected to measure all standard AMS species routinely (e.g., 10 Be, 14 C, 26 Al, 36 Cl, 41 Ca, and 129 I). 14 C-AMS using a CO 2 gas-ion source is intended to improve lowbackground and high-repeatability measurements.…”

“…The L2 beam course has a large environmental testing chamber (1 m diameter) that will be mainly used for the radiation-resistant testing of semiconductor devices for space satellites. The L3 beam course is constructed as follows: the Oxford microbeams quadrupole lens system [9] is used to obtain spot diameters of the order of 1 lm and below, and a superconducting detector [10] is used for high-sensitivity PIXE analysis. The L4 beam course is the rare-particle detection system for AMS.…”

“…The rare-particle detection system on the tandem accelerator (Tsukuba 6 MV AMS system) is designed for the high-sensitivity http://dx.doi.org/10.1016/j.nimb.2015.04.028 0168-583X/Ó 2015 Elsevier B.V. All rights reserved. detection of 10 Be, 14 C, 26 Al, 36 Cl, 41 Ca, and 129 I, and is expected also to measure other radioisotopes such as 32 Si and 90 Sr.…”

112-Pixel Arrays of High-Efficiency STJ X-Ray Detectors

“…For this reason, Nb-based STJs have been used for a decade in bioenvironmental and material science applications at the synchrotron [1,[3][4][5]. More recently, STAR Cryoelectronics has developed STJs based on tantalum, since its high atomic number (Z Ta = 73) increases the quantum efficiency, and its small energy gap (Δ Ta = 0.7 meV) improves the energy resolution over earlier Nb-based STJs.…”