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.

A multi-layered MoS 2 film was formed on a SiO 2 film by high-temperature sputtering, which is one of the alternative methods of Si LSI technology. It was found that the carrier density of a sputter-deposited MoS 2 film is 1000 times smaller than that of an exfoliated one. By sputtering, two different orientations, namely a layer lateral to a SiO 2 /Si substrate and a layer perpendicular to the substrate, were formed. The lateral layer showed a lower carrier density than the perpendicular layer because of the decrease in the number of sulfur vacancies, as commonly discussed in several research studies. However, the vacancies are not sufficient for describing this significant reduction in carrier density. It is considered that a sodium ion functioning as an interface trapped charge is one of the main origins of carriers. Sputtering, which enables us to determine the sodium contamination level, can be seen as appropriate for reducing the carrier density; hence, this method is considered to be efficient in realizing enhancement-mode MoS 2 MOSFETs. In addition, sputtering also enable us to form large-scale MoS 2 films up to a wafer size. Therefore, a sputterdeposited MoS 2 film is a promising material for post-silicon devices.

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Solid-phase crystallization of Si1−xGex (x=0–1.0) alloy layers deposited on a Si (100) substrate was investigated by ellipsometric spectroscopy. From a dispersion analysis of dielectric spectra, we deduced a crystallinity corresponding to the degree of average lattice alignment of the composed polycrystalline Si1−xGex layers and investigated the dynamical change in crystallinity during crystallization. We found that the crystallinity and crystallization temperature (TC) rapidly decreased with increasing Ge concentration (x). When x was small (=0–0.3), the highest crystallinity was ∼0.8 of that for single crystals while the lowest one was considerably below 0.6 when x>0.8. Moreover, the crystallinity decreased with increasing temperature above TC. We investigated the nucleation rate during crystallization and found that the decrease in crystallinity at both large Ge concentration and high temperature can be explained by a trade-off between the nucleation and crystallization rates; nucleation was dominant under these conditions. An overview of the crystallinity of solid-phase crystallized Si1−xGex alloy layers is provided.

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