We experimentally studied an impact of the surface oxide layer on quantum confinement effects (QCE) in Si quantum well (SQW) structures (surface-oxide/two-dimensional-Si/buried-oxide) with various surface oxide layer thickness T OX on silicon-on-insulator (SOI) substrate, by UV-Raman spectroscopy, photoluminescence (PL) method, and two-dimensional (2D) stress simulator. UV-Raman data show that tensile strain ε of SQW, stressed by a thermal expansion mismatch between surface oxide and Si layers, decreases with decreasing the T OX . According to the strain behavior in the SQW and strained-Si on strained-SOI, PL results show that bandgap E G of the SQW rapidly expands with decreasing T OX . As a result, we can estimate the E G of the fully relaxed SQW. However, QCE in SQW keep thermally stable, in spite of carrying out a high temperature N 2 annealing process.

We experimentally studied the material structures of two-/three-dimensional (2D/3D) silicon carbon layers Si1−YCY with Y ≤ 0.25 and 5 ≤ NL ≤ 162 [NL is the atomic layer number of Si1−YCY)] on buried oxide (BOX), which were fabricated by hot-C+-ion implantation into a (100) silicon-on-insulator (SOI) substrate before an oxidation process. A 2D Si layer was also fabricated as a reference. The C 1s spectrum obtained by X-ray photoemission spectroscopy shows that the implanted C atoms segregate at the oxide interface. Using a scanning transmission electron microscope and a high-resolution scanning transmission electron microscope to observe cross sections of Si0.75C0.25 layers, 2-nm-thick 3C-SiC layers were found be partially formed in the C segregation layer near the BOX interface. At Y > 0.1 and 5 ≤ NL ≤ 162, we observed very strong photoluminescence (PL) emission in the UV/visible regions from a 3C-SiC area and a Si1−YCY area in the C segregation layer, whereas a 2D Si emitted weak PL photons only at NL < 10. Thus, the silicon carbon technique is very promising for Si photonics and bandgap engineering in CMOS.

We experimentally studied the effects of the C atom on bandgap E G modulation in two-dimensional (2D) silicon carbon alloys, Si 1%Y C Y , fabricated by hot C + ion implantation into the (100) SOI substrate in a wide range of Y (4 ' 10 %5 : Y : 0.13), in comparison with the characteristics of 3D silicon carbide (SiC). X-ray photoelectron spectroscopy (XPS) and UV-Raman analysis confirm the Si-C, CC , and Si-Si bonds in the 2D-Si 1%Y C Y layer. The photoluminescence (PL) method shows that the E G and PL intensity I PL of 2D-Si 1%Y C Y drastically increase with increasing Y for high Y (;0.005), and thus we demonstrated a high E G of 2.5 eV and a visible wavelength λ PL less than 500 nm. Even for low Y (<10 %3), I PL of 2D-Si 1%Y C Y also increases with increasing Y, owing to the compressive strain of the 2D-Si 1%Y C Y layer caused by the C atoms, but the Y dependence of E G is very small. E G of 2D-Si 1%Y C Y can be controlled by changing Y. Thus, the 2D-Si 1%Y C Y technique is very promising for new E G engineering of future high-performance CMOS and Si photonics.

Doxorubicin (DOX) is a highly potent anti-neoplastic agent widely used in clinical practice, but its dosage and duration of administration are strictly limited due to dose-related organ damage. In the present study, we examined whether theanine, an amino acid derivative found in green tea leaves, can protect against DOX-induced acute nephrotoxicity in rats. Decreases in the creatinine clearance by DOX administration were attenuated by concurrent treatment with theanine, which was consistent with the change in histological renal images assessed by microscopic examination. Theanine had no effect on the distribution of DOX to the kidney. The production of lipid peroxide in the kidney after DOX administration was suppressed by concurrent treatment with theanine. Reduced glutathione content, but not superoxide dismutase activity, was decreased following DOX administration, whereas this change was suppressed when theanine was given in combination with DOX. These results suggest that theanine prevents DOX-induced acute nephrotoxicity through its antioxidant properties.

Crystal direction dependence of quantum confinement effects of two-dimensional Si layers fabricated on silicon-on-quartz substrates: modulation of phonon spectra and energy band structures View the table of contents for this issue, or go to the journal homepage for more 2014 Jpn. J. Appl. Phys. 53 04EC09