Ultra-thin single crystal silicon with the (100) surface formed by the local-oxidation-of-silicon (LOCOS) on a silicon-oninsulator (SOI) substrate becomes a quasi-direct band-gap semiconductor due to the quantum mechanical confinement effect. The device is a simple pn diode in a planar structure. Electro-luminescence (EL) has been observed by the lateral carrier injections into the two-dimensional quantum well.

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Negative bias temperature instability (NBTI) of pMOSFETs with ultra-thin gate dielectrics was investigated from four points of view: basic mechanism of NBTI, dependence of NBTI on gate dielectric thickness, mechanism of NBTl enhancement caused by addition of nitrogen to the gate dielectrics, and possibility of applying SiON gate dielectrics with a high concentration of nitrogen. By investigating the behavior of FET characteristics after NBT stresses were stopped, it was clarified that a portion (60%, in our case) of hydrogen atoms released by the NBT stress remain in the gate dielectric in the case of a 1.85-nm-thick NO-oxynitride gate dielectric. The existence of the hydrogen was shown to lead to the generation of. positive fixed charges in the gate dielectric. It was also found that NBTI depends little on gate dielectric thickness. Moreover, we revealed that the origin of NBTl enhancement by incorporating nitrogen into gate dielectrics is the property of attracting H,O or OH. We speculate this property of attracting H,O or OH is due to the existence of positive fixed charges induced by undesirable nitrogen. We evaluated NBTl immunity of SiN gate dielectrics with oxygen-enriched interface (01-SiN) in which high carrier mobility was obtained by reducing positive fixed charges. The 01-SiN gate dielectrics with EOTs of 1.4 and 1.6 nm were found to have sufticient.lifetime for practical use under 1 V operation.

We have observed net optical gain by current injections to ultra-thin Si embedded in a resonant optical cavity. The cavity consists of a dielectric waveguide fabricated by CMOS and MEMS process. The photoluminescence (PL) spectra show narrow resonances peaked at the designed wavelength, and the electroluminescence (EL) intensity increases super-linearly with currents. The comparisons with first principle calculations suggest that the optical gain is originated from intrinsic material properties of ultra-thin Si due to quantum confinements.

We propose a germanium fin light-emitting diode for a monolithic light source on a Si photonics chip. The germanium fins were fabricated by the oxidation condensation of silicon-germanium sidewalls epitaxially grown on silicon fins. We found that a tensile stress is applied to the pure germanium fins by the difference of the thermal expansion coefficient with that of the surrounding oxide. The electroluminescence spectra were consistent with those expected from direct recombination in germanium with a tensile stress. The strong immunity of germanium fins against high current densities would be favourable to achieve population inversions by electrical pumping.