Hitachi, Ltd.

Hitachi Automotive Systems, Ltd.

Toshiyuki Usagawa

Susumu Takahashi

Yoshinori Imamura

Shigeo Goto

Ken Yamaguchi

Kenji Hiruma

Tomonori Tanoue

Hiroyuki Itoh

Kensuke Ogawa

Yuichi Ono

Yasuhiro Shiraki

Shinichiro Takatani

Atsushi Takai

Masao Yamane

Masayoshi Kobayashi

Katsuhiko Mitani

Masahiko Kawata

Hidekazu Okuhira

Yasunari Umemoto

Toshihisa Tsukada

Yoshitaka Sasago

Kiichi Ueyanagi

Toshiaki Masuhara

Tsuyoshi Hasegawa

Hitoshi Nakamura

Eiichi Maruyama

Shigeyuki Hosoki

Toshio Katsuyama

Kazuo Ono

Toshiyuki Aida

Hiroshi Kakibayashi

Shirun Ho

Norikazu Hashimoto

Yoshifumi Katayama

Masakazu Ichikawa

Yoshimasa Murayama

Yasushi Sawada

Makiko Kohno

Hitoshi Nakahara

Yoshiaki Takemura

Gerard P Morgan

Keiichi Haraguchi

Masamits Yazawa

Masashi Kawasaki

Kenichi Tominaga

Akemi Sawada

In a gas sensor using a first FET-type sensor for a sensor unit, a gas density measurement unit measures a gas density of gas to be detected at a predetermined time on the basis of a first threshold change as a difference between a first threshold voltage applied to a first gate layer when a first source-drain current is a first threshold current while the gas to be detected is not present in the atmosphere and a second threshold voltage applied to the first gate layer when the first source-drain current is the first threshold current at the predetermined time while the gas to be detected is present in the atmosphere, and a temporal differentiation of the first threshold change.

Gas sensor

The invention achieves a lower noise of a sense signal of a FET-type hydrogen sensor. For solving the above problem, one aspect of a sensor system of the invention includes a reference device and a sensor device configured using FETs on a substrate, and further, well potentials of the reference device and the sensor device are electrically isolated from each other.

Sensor system and device

A semiconductor gas sensor includes a CMOS inverter which is configured by an n-channel field effect transistor having a catalytic gate and a p-channel field effect transistor having the catalytic gate. An input setting gate potential Vin(D) of the CMOS inverter is set to satisfy 'Vin(D)=Vtc&#x2212;&#x394;Vgth' by using the sensor response threshold intensity &#x394;Vgth determined by a concentration of a gas to be detected and a threshold input potential Vtc of the CMOS inverter. Therefore, only by setting the input setting gate potential Vin(D), a warning or an alarm can be issued for the concentration of the gas to be detected. In addition, a temperature compensation of the threshold voltage caused by a MOS structure is reduced regardless of the detection gas by setting a characteristic coefficient &#x3b2;, a threshold voltage Vtn of the n-channel field effect transistor, and the threshold voltage Vtp of the p-channel field effect transistor so as to satisfy relations '&#x3b2;=1' and &#x201c;Vtp=&#x2212;Vtn&#x201d;.

Semiconductor gas sensor

A technique capable of realizing a semiconductor gas sensor having a high rising response speed is provided. A gate insulating film (e.g., a SiOfilm) is formed on a Si layer, and a modified TiOx (a TiOx nanocrystal) film is formed on the gate insulating film. Further, on the modified TiOx film, a Pt film is formed. This Pt film is composed of a plurality of Pt crystal grains, and in a crystal grain boundary gap existing among the plurality of Pt crystal grains, Ti and oxygen (O) are present, and particularly, a TiOx nanocrystal is formed on a surface in the vicinity of a grain boundary triple point as the center.

Semiconductor gas sensor and method for producing the same

The gas sensor has a substrate, a gate insulating film arranged on the substrate, and a gate electrode arranged on the gate insulating film, wherein the gate electrode comprises a metal oxide mixture film produced by mixing an oxygen-doped amorphous metal that contains oxygen with crystals of an oxide of the metal and a platinum film formed on the metal oxide mixture film, the platinum film is composed of multiple platinum crystal grains and grain boundary regions that are present between the platinum crystal grains, the grain boundary regions are filled with a metal oxide mixture, and each of the platinum crystal grains is surrounded by the metal oxide mixture.

Gas sensor and a method of manufacturing the same

A MISFET-type hydrogen gas sensor having low power consumption which can be operated for one year or longer at a low voltage power source (for example, 1.5 to 3 V) is achieved. A sensor FET is formed in a MEMS regionwhere a Si substrateof a SOI substrate is bored, and a heater wiringis arranged so as to be folded between a Pi-Ti&#x2014;O gateand a source electrodeS of the sensor FET and between the Pt&#x2014;Ti&#x2014;O gateand a drain electrodeD thereof, respectively. Further, a plurality of through-holesobtained by removing a protective film so as to expose an embedded insulation layer of the SOI substrate are formed in a region where an intrinsic FET regionwhere the sensor FET is formed does not overlap with the MEMS regionand except for bridge regionsS,G, andH where lead-out wiringsS,D,G, andH are formed and except for reinforced regions

A compact, lightweight, and easy-to-use ESR-CT apparatus including a magnetic field leak line (5-G line) which is capable of imaging a small animal, such as a mouse, within 15 minutes, and of observing a desired region with a spatial resolution of 1 mm or less. A permanent magnet system is introduced of the apparatus includes pole pieces having a predetermined area which are opposed to each other through a measured space, yokes combined with the pole pieces, and a permanent magnet inserted in series so that at least one magnetic pole plane intersects perpendicularly to the closed magnetic circuit for magnetic coupling with the yokes. This makes it possible to locate a gradient coil system and a field scanning coil system sufficiently apart from end faces of the pole pieces, and to downsize the field scanning coil system so that the gradient field system is movable.

Apparatus for electron spin resonance CT

Method and apparatus for forming microstructure body

A semiconductor device is diclosed which has a PN-junction gate field effect transistor constituting a PN-junction gate with a semiconductor layer of opposite conductivity, an undoped semiconductor layer, and an active layer by depositing sources and drains made of semiconductor layers on the active layer of uniconductivity, depositing an undoped semiconductor layer whose band gap is greater than that of the active layer on the active layer between the opposing end surfaces of the sources and drains, and depositing a semiconductor layer of opposite conductivity on the undoped semiconductor layer away from the sources and drains. In particular, the present invention is effective for an enhancement type PN-junction power FET using compound semiconductors such as GaAs and capable of running with a single power supply and for a semi-conductor device integrating the enhancement type PN-junction power FET and a high-frequency low noise amplifier mono-lithically.

PN-junction gate FET

A semiconductor device may include a double hetero junction bipolar transistor and a field-effect transistor. The base of the bipolar transistor and the gate of the field-effect transistor are connected to each other to serve as an input terminal and the collector of the bipolar transistor and the drain of the field-effect transistor are connected to each other to serve as an output terminal. The bipolar transistor and the field-effect transistor may be created on a common substrate. In this case, both the bipolar and field-effect transistors can have the same multilayer/film structures.

Semiconductor device

Superconductized electronic devices, such as a Josephson junction device, or superconductized optical devices represented by a light emitting and receiving devices of semiconductor laser are available using semiconductor materials which normally have no superconducting characteristics. The devices can operate by controlling the behavior of a Cooper pair in an active region which is formed in the semiconductor in advance using the penetrating phenomenon of the Cooper pair caused in the semiconductor proximate to the superconductor.

Superconductized semiconductor device using penetrating Cooper pairs

This invention discloses a heterojunction type field effect transistor such as 2DEG-FET and a heterojunction type bipolar transistor such as 2DEG-HBT. The former is fabricated by applying to the formation of its source and drain regions a technique which causes the disorder of the heterojunction by intoduction of an impurity such as by ion implantation or a technique which causes the disorder of the heterojunction by forming a film made of at least one kind of material selected from insulators, metals and semiconductors which have a different linear coefficient of thermal expansion from that of the material of a semiconductor substrate on the heterojunction semiconductor region which is to be disordered. The latter is fabricated by applying either of the techniques described above to a base ohmic contact region. These semiconductor devices can reduce the source-gate resistance and the parasitic base resistance. The invention discloses also the structure of the ohmic contact layer which has a trench on the surface thereof and is particularly effective for reducing the source-gate parasitic resistance.

Semiconductor device having a heterojunction and a two dimensional gas

Source and drain electrode metals of a field effect transistor having a recessed gate electrode metal are directly connected to a high impurity concentration semiconductor layer which faces the gate electrode metal through an insulator film which defines the side wall of the recess. The source and drain electrode metals may be disposed so as to face the gate electrode metal through the side insulator film. With this arrangement, it is possible to lower the parasitic resistance between the gate electrode and another electrode of the field effect transistor, to lower the contact resistance between a semiconductor layer and the source and drain electrodes, to reduce the capacitance of the recess gate electrode and to increase the source-gate breakdown voltage, advantageously. The above-described arrangement is particularly suitable for a transistor employing a compound semiconductor, and can also be applied to semiconductor devices other than field effect transistors. Such semiconductor devices can readily be produced by forming a gate electrode metal with a self-alignment process using the lift-off method.

Semiconductor device and method of producing the same

A semiconductor light-emitting device includes a plurality of semiconductor rods, each of which has a pn junction. The semiconductor rods are formed on a semiconductor substrate such that the plurality of semiconductor rods are arranged at a distance substantially equal to an integer multiple of the wavelength of light emitted from the semiconductor rod. With such devices, various novel optical devices such as a micro-cavity laser of which the threshold current is extremely small and a coherent light-emitting device having no threshold value can be realized.

Semiconductor optical device with nanowhiskers

In a high speed logic circuit using a vertical hetero-junction bipolar transistor, in which two-dimensional carriers formed at a semiconductor hetero-junction interface are used as a base layer, the uppermost layer being a collector layer, the lowest layer being an emitter layer, two base electrodes making contact with the base layer are disposed so as to put a collector electrode, which is electrically in contact with the collector layer, therebetween. The base electrodes are used at the same time as a source electrode and a drain electrode, respectively, of a field effect transistor using the two-dimensional carriers as an active layer. The high speed logic circuit is so constructed that one of the base electrodes of the bipolar transistor is an input terminal; the other is connected with a power supply; the emitter is grounded; and the collector is an output terminal.

High speed logic circuit

Growing community of inventors

Yono, Japan

Toshiyuki Usagawa