Fujitsu Corporation

Yoshihiro Sugiyama

Yoshiaki Nakata

Shunichi Muto

Yoshiki Sakuma

Hitoshi Tanaka

Yasuyuki Tamura

Atsushi Takeuchi

Kanetake Takasaki

Kenichi Imamura

Toshio Fujii

Naoto Horiguchi

Kiyoshi Irino

Yoshiaki Tanida

Chikako Yoshida

Yoshihiro Sugita

Tsuguo Inata

Hideaki Ishikawa

Yusuke Morisaki

Shun-ichi Muto

Takayuki Aoyama

A semiconductor memory device which more reliably retains electrons trapped in its charge-trapping regions. A high-dielectric gate insulating film is grown on a semiconductor substrate. This gate insulating film is composed of first and second oxides, where the second oxide has a smaller bandgap than that of the first oxide and is scattered in dot-like form, surrounded by the first oxide. The memory cell is programmed by injecting electrons into a local potential minimum that is produced due to the bandgap difference between the phase-separated first and second oxides.

Semiconductor memory device and manufacturing method thereof

The semiconductor device comprises an intermediate layer formed on a semiconductor substrate, the intermediate layerbeing formed of an oxide containing a first element which is either of a III group element and a V group element, an insulation film formed on the intermediate layer, the insulation film being formed of an oxide of a second element which is the other of the III group element and the V group element, and an electrodeformed on the insulation film. Because the intermediate layer of the oxide containing the first element is formed, even when the gate insulation film is formed of AlOor others, the interface state density can be depressed to be low. Thus, the semiconductor device can have low interface state density and small flat band voltage shift even when AlO, etc. is used as a material of the insulation film.

Semiconductor device having low interface state density and method for fabricating the same

A semiconductor device in which the insulation characteristics of an insulating film of multilayer structure including a lower-layer insulating film and a high-dielectric-constant film formed on the lower-layer insulating film are ensured, and a method for fabricating such a semiconductor device. A silicon oxide film or a silicon oxynitride film is formed on a semiconductor substrate as a lower-layer insulating film and part of the lower-layer insulating film is removed. Then a high-dielectric-constant film the dielectric constant of which is higher than that of the lower-layer insulating film is formed on the exposed semiconductor substrate and the lower-layer insulating film. If the lower-layer insulating film is a silicon oxide film, then a metallic compound not including chlorine is used for forming this high-dielectric-constant film. If the lower-layer insulating film is a silicon oxynitride film, then a metallic chloride can be used for forming this high-dielectric-constant film.

Semiconductor device and method for fabricating the same

A quantum semiconductor device includes intermediate layers of a first semiconductor crystal having a first lattice constant and stacked repeatedly, and a plurality of quantum dots of a second semiconductor crystal having a second lattice constant different from the first lattice constant. The quantum dots are dispersed in each of the intermediate layers and form a strained heteroepitaxial system with respect to the corresponding intermediate layer. Each of the quantum dots has a height substantially identical with a thickness of the corresponding intermediate layer.

Quantum semiconductor device including quantum dots and a fabrication process thereof

A photodetector includes a substrate and an optical absorption layer provided on the substrate, wherein the optical absorption layer is formed of a mixed crystal of Si, Ge and C.

Photodetector having a mixed crystal layer of SiGeC

A quantum semiconductor memory device includes a quantum structure formed on a substrate, wherein the quantum structure includes a plurality of self-organized quantum dots forming a strained heteroepitaxial system with respect to the substrate and an accumulation layer formed adjacent to the self-organized quantum dots, and wherein the self-organized quantum dots are formed of a semiconductor crystal having a composition set such that quantum levels of the self-organized quantum dots are located higher than a conduction band of the accumulation layer.

Quantum semiconductor memory device including quantum dots

In a semiconductor device, concave sections in which an opening area becomes small in proportion as a depth becomes deep are formed in a crystal layer, and a quantum structure is formed on at least one crystal face of a bottom section of the concave section and a border formed between plural sidewalls thereof. In case the quantum structure is formed in the bottom section, a quantum box is formed therein. If the quantum structure is formed in the border between the sidewalls of the concave section, a quantum wire is formed therein. In case the quantum structure is formed in the sidewall of the concave section, a two-dimensional quantum well is formed therein.

Semiconductor device and method of fabricating the same

A quantum semiconductor device includes a plurality of intermediate layers stacked on each other repeatedly, each being formed of a first semiconductor crystal having a first lattice constant and including a plurality of quantum dots of a second semiconductor crystal having a second lattice constant different from the first lattice constant, the second semiconductor crystal forming thereby a strained system with respect to the first semiconductor crystal, each of the quantum dots in an intermediate layer having a height substantially identical with a thickness of the intermediate layer, each quantum dot in an intermediate layer aligning with another quantum dot in an adjacent intermediate layer in a direction perpendicular to a principal surface of the intermediate layer, each of the intermediate layers having a thickness equal to or smaller than a Bohr-radius of carriers in said intermediate layer, wherein the second semiconductor crystal contains N.

Quantum semiconductor device having a quantum dot structure

A wavelength-domain-multiplication memory comprises a first semiconductor layer including a first conductivity type impurity, a carrier barrier semiconductor layer formed on the first semiconductor layer, and quantum dots formed in the carrier barrier semiconductor layer.

Optical semiconductor memory device and read/write method therefor

An active layer having a predetermined effective band gap, a predetermined effective refractive index, and a predetermined thickness is sandwiched between a first clad layer and a second clad layer. Each of the clad layers has an effective band gap wider than that of the active layer, an effective refractive index lower than that of the active layer, and a predetermined thickness. On the first clad layer, there is disposed a first stack structure doped to a first conductivity type, which alternately includes a layer of a high refractive index and a layer of a low refractive index, and has a discontinuity of a band of the first conductivity type made quite smaller than that of a band of a second conduction type. On the second clad layer, there is disposed a second stack structure doped to the second conductivity type, which alternately includes a layer of a high refractive index and a layer of a low refractive index, and has a discontinuity of a band of the second conductivity type made quite smaller than that of the band of the first conductivity type. Each of the first and second stack structures serves as an optical filter and also forms a low-resistance conduction path.

Vertical optoelectronic semiconductor device

In an optosemiconductor device including a superlattice configuration (TBQ) of first and second quantum well layers and a potential barrier therebetween, photo-excited carriers are formed in the first quantum well layer and are tunnelled through the potential barrier toward the second quantum well layer, so that the tunneled carriers are accumulated in the second quantum well layer. An electric field is applied to the superlattice configuration to expel the tunneled carriers from the second quantum well layer.

High speed optosemiconductor device having multiple quantum wells

A resonant tunnelling barrier (RTB) structure device (e.g., diode), having a large peak-to-valley current density (Jp/Jv) ratio, includes an InP substrate and a RTB structure structure. The RTB structure is formed by a first doped layer of InP or In.sub.0.53 GA.sub.0.47 As, a first barrier layer of Al.sub.x Ga.sub.1-x As.sub.y Sb.sub.1-y (0.ltoreq.x.ltoreq.1, y=0.51+0.05x), a well layer of InP or In.sub.z Ga.sub.1-z As (0.52.ltoreq.z.ltoreq.0.54), a second barrier layer of the AlGaAsSb, and a second doped layer of InP or In.sub.z Ga.sub.1-z As. The layers of the RTB structure are lattice-matched to InP.

Growing community of inventors

Kawasaki, Japan

Yoshihiro Sugiyama