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 optimization of the hot-C + -ion implantation process for forming nano-SiC (silicon carbide) regions in a (100) Si-oninsulator substrate at various hot-C + -ion implantation temperatures and C + ion doses to improve photoluminescence (PL) intensity for future Sibased photonic devices. We successfully optimized the process by hot-C + -ion implantation at a temperature of about 700 °C and a C + ion dose of approximately 4 ' 10 16 cm %2 to realize a high intensity of PL emitted from an approximately 1.5-nm-thick C atom segregation layer near the surface-oxide/Si interface. Moreover, atom probe tomography showed that implanted C atoms cluster in the Si layer and near the oxide/Si interface; thus, the C content locally condenses even in the C atom segregation layer, which leads to SiC formation. Corrector-spherical aberration transmission electron microscopy also showed that both 4H-SiC and 3C-SiC nanoareas near both the surface-oxide/Si and buried-oxide/Si interfaces partially grow into the oxide layer, and the observed PL photons are mainly emitted from the surface SiC nano areas.

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.

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