The atomically smooth SrTiO(3) (100) with steps one unit cell in height was obtained by treating the crystal surface with a pH-controlled NH(4)F-HF solution. The homoepitaxy of SrTiO(3) film on the crystal surface proceeds in a perfect layer-by-layer mode as verified by reflection high-energy electron diffraction and atomic force microscopy. Ion scattering spectroscopy revealed that the TiO(2) atomic plane terminated the as-treated clean surface and that the terminating atomic layer could be tuned to the SrO atomic plane by homooepitaxial growth. This technology provides a well-defined substrate surface for atomically regulated epitaxial growth of such perovskite oxide films as YBa(2)Cu(3)O(7-delta).

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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.

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.

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