We have investigated the IR photoluminescence (PL) behavior of Cu‐doped β‐FeSi2 nanocrystals (β‐NCs) embedded in Si layers. The diffusion rate of Cu atom was controlled by annealing. The most appropriate condition brought the largest intensities of both the intrinsic A band emission at 0.803 eV by 214% and the acceptor related C band emission at ∼0.75 eV by 582% in comparison with those of non‐doped β‐NCs. Rutherford backscattering spectrometry (RBS) revealed increase of Cu atoms in the Si layer with β‐NCs with increasing the anneal duration. The C band enhancement surely is originated from increase of a density of state at acceptor levels relating to increase of Cu in β‐lattice. Photocarrier injection PL measurements (PCI‐PL) reveal that the enhancement of the A band emission may be attributed to a controlled migration process of holes with a repeated trap process due to Cu‐doping into the Si phase. This dynamic condition leads to an increase of valence band offset at the β‐NCs/Si heterointerfaces where the migration of holes from the β‐NCs to Si is prevented, so that a radiative recombination rate can be enhanced. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

We have investigated atomic ordering of Heusler alloy Fe3Si(111) epitaxially grown on Si(111) by using ion beam analysis. The total atomic displacement along Si<111> directions was deduced from the minimum yield χmin and the critical angle Ψ1/2 for channeling. The total displacement consists of both one‐dimensional thermal vibrations computed by the Debye theory and static displacements due to imperfections, lattice mismatch, thermal expansion etc. The atomic displacement increased as the annealing temperature increased from 373 to 573 K. We found that this static displacement came from a difference in thermal expansion between the Fe3Si film and Si substrates at the anneal temperature and was quenched into room temperature as a remnant displacement. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

We have investigated photoluminescence (PL) behaviors of nano-composite phase of -NCs embedded in SiO2 (-NCs/SiO2). The inhomogeneous spectra consisting of the A, B and C emission bands were observed. PL enhancement also was confirmed in comparison with -NCs/Si. Under high pumping rate, we observed PL spectra near room temperatures (~270 K). This fact means that oxidation of the nano-composite phase can contribute to reduction of thermal quenching, which may come from increase of band offsets around NCs. .

We have investigated photoluminescence (PL) behaviors of nano-composite phase of -NCs embedded in SiO2 (-NCs/SiO2). The inhomogeneous spectra consisting of the A, B and C emission bands were observed. PL enhancement also was confirmed in comparison with -NCs/Si. Under high pumping rate, we observed PL spectra near room temperatures (~270 K). This fact means that oxidation of the nano-composite phase can contribute to reduction of thermal quenching, which may come from increase of band offsets around NCs..

We have investigated oxidation behaviors of nano-composite phase with -FeSi2 nanocrystals (-NCs) and Si on Si substrates. IR absorption measurements revealed that only oxidation of Si into SiO2 proceeded in the nano-composite phase. This fact is very important for realization of a novel composite phase with -NCs and SiO2, which may contribute to enhancement of light emission and to prevent a large thermal quenching of light emission observed in the composite phase with -NCs and Si.