Abstract: A magnetoresistance device comprises a substrate, an elongate semiconductor channel extending in a first direction and at least two conductive leads providing a set of contacts to the channel. The device may comprise an optional semiconductor shunt in contact with the channel. The optional shunt, channel and set of contacts are stacked relative to the substrate in a second direction which is perpendicular to the first direction and the surface of the substrate. The device has a side face running along the channel. The device is responsive to a magnetic field generally perpendicular to the side face.

Abstract: There is disclosed a variable-gain amplifier circuit that operates on a low voltage, exhibits low distortion, provides a wide range of variation, and is suitable for use in a low-power-consumption wireless communication system. The variable-gain amplifier circuit is configured so that a variable-load circuit, which includes three reactance function elements and provides a wide range of impedance variation, is connected to a conductor circuit whose output terminal generates a positive-phase output current proportional to conductance with respect to an input voltage.

Abstract: The present invention provides a semiconductor integrated circuit including an active mixer circuit that is operated at low voltage, low noise, and low power consumption. It includes a transconductance amplifier, a transformer, and a multiplier, connects a transformer between the transconductance amplifier and the multiplier, and separates between the transconductance amplifier and the multiplier with respect to direct current inside the transformer. Further, each of the tranconductance amplifier and the multiplier is configured of transistors that are single-stacked between the supply voltage terminal and ground terminal.

Abstract: A magnetoresistance device comprises a substrate, an elongate semiconductor channel extending in a first direction and at least two conductive leads providing a set of contacts to the channel. The device may comprise an optional semiconductor shunt in contact with the channel. The optional shunt, channel and set of contacts are stacked relative to the substrate in a second direction which is perpendicular to the first direction and the surface of the substrate. The device has a side face running along the channel. The device is responsive to a magnetic field generally perpendicular to the side face.

Abstract: A semiconductor device capable of avoiding generation of a barrier in a conduction band while maintaining high withstanding voltage and enabling high speed transistor operation at high current in a double hetero bipolar transistor, as well as a manufacturing method thereof, wherein a portion of the base and the collector is formed of a material with a forbidden band width narrower than that of a semiconductor substrate, a region where the forbidden band increases stepwise and continuously from the emitter side to the collector side is disposed in the inside of the base and the forbidden band width at the base-collector interface is designed so as to be larger than the minimum forbidden band width in the base, whereby the forbidden band width at the base layer edge on the collector side can be made closer to the forbidden band width of the semiconductor substrate than usual while sufficiently maintaining the hetero effect near the emitter-base thereby capable of decreasing the height of the energy barrier gene

Abstract: There is disclosed a variable-gain amplifier circuit that operates on a low voltage, exhibits low distortion, provides a wide range of variation, and is suitable for use in a low-power-consumption wireless communication system. The variable-gain amplifier circuit is configured so that a variable-load circuit, which includes three reactance function elements and provides a wide range of impedance variation, is connected to a conductor circuit whose output terminal generates a positive-phase output current proportional to conductance with respect to an input voltage.

Abstract: The present invention provides a semiconductor integrated circuit including an active mixer circuit that is operated at low voltage, low noise, and low power consumption. It includes a transconductance amplifier, a transformer, and a multiplier, connects a transformer between the transconductance amplifier and the multiplier, and separates between the transconductance amplifier and the multiplier with respect to direct current inside the transformer. Further, each of the tranconductance amplifier and the multiplier is configured of transistors that are single-stacked between the supply voltage terminal and ground terminal.

Abstract: A bipolar transistor is provided in which both the base resistance and the base-collector capacitance are reduced and which is capable of operating at a high cutoff frequency. The semiconductor device is structured so that the emitter and extrinsic base are separated from each other by an insulator sidewall and the bottom faces of the insulator sidewall, and the emitter are approximately on the same plane. The extrinsic base electrode and the collector region are separated from each other by an insulator.

Abstract: A high quality silicon carbide (SiC) layer being substantially lower in threading dislocation density than a prior layer is formed on silicon (Si) substrate. A semiconductor device is fabricated in such a way that a semiconductor buffer layer containing Si in part and being higher in defect density than a Si substrate is formed on the Si substrate on the upper portion of which are formed a plurality of pairs of facets being mirror-symmetrical to the surface orientation of a semiconductor substrate, further on the top of the layer a SiC layer is sequentially formed.

Abstract: A bipolar type semiconductor device capable of attaining high current gain and high cut-off frequency and performing a satisfactory transistor operation also in a high current region while maintaining a high breakdown voltage performance, as well as a method of manufacturing the semiconductor device, are provided. In a collector comprising a first semiconductor layer and a second semiconductor layer narrower in band gap than the first semiconductor layer, an impurity is doped so as to have a peak of impurity concentration within the second collector layer and so that the value of the peak is higher than the impurity concentration at any position within the first collector layer. It is preferable to adjust the concentration of the doped impurity in such a manner that a collector-base depletion layer extends up to the first collector layer.

Abstract: A semiconductor device capable of avoiding generation of a barrier in a conduction band while maintaining high withstanding voltage and enabling high speed transistor operation at high current in a double hetero bipolar transistor, as well as a manufacturing method thereof, wherein a portion of the base and the collector is formed of a material with a forbidden band width narrower than that of a semiconductor substrate, a region where the forbidden band increases stepwise and continuously from the emitter side to the collector side is disposed in the inside of the base and the forbidden band width at the base-collector interface is designed so as to be larger than the minimum forbidden band width in the base, whereby the forbidden band width at the base layer edge on the collector side can be made closer to the forbidden band width of the semiconductor substrate than usual while sufficiently maintaining the hetero effect near the emitter-base thereby capable of decreasing the height of the energy barrier gene

Abstract: There is provided not only a radio frequency power amplifier using an SiGe HBT subject to a little amplification distortion, but also a communication system using the same. A conventional radio frequency power amplifier provides base bias paths of transistors Q1 through QN (SiGe HBT) with bias resistors R11 through R1N having resistance values three to five times higher than those of a ballast resistor attached to each transistor's base. A coil LB is provided in parallel with the bias resistor as a means for compensating a voltage drop due to direct current component IDC flowing through the bias resistor. Addition of the bias resistor suppresses non-linearity of low-frequency variations in an output current. Addition of the coil compensates for voltage drop. Accordingly, the maximum linear output power can be improved. As a result, it is possible to provide the power amplifier subject to a little amplification distortion within a wide output range.

Abstract: An (SiGe)C layer having a stoichiometric ratio of about 1:1 is locally formed on an Si layer, a large forbidden band width semiconductor device is prepared inside the layered structure thereof and an Si semiconductor integrated circuit is formed in the regions not formed with the layered structure, whereby high frequency high power operation of the device is enabled by the large forbidden band width semiconductor device and high performance is attained by hybridization of the Si integrated circuit.

Abstract: A high quality silicon carbide (SiC) layer being substantially lower in threading dislocation density than a prior layer is formed on silicon (Si) substrate. A semiconductor device is fabricated in such a way that a semiconductor buffer layer containing Si in part and being higher in defect density than a Si substrate is formed on the Si substrate on the upper portion of which are formed a plurality of pairs of facets being mirror-symmetrical to the surface orientation of a semiconductor substrate, further on the top of the layer a SiC layer is sequentially formed.

Abstract: A bipolar semiconductor device including a collector layer covered at a portion of an outer periphery thereof with an insulating film and having a shape extending in an upper direction and a horizontal direction, with a gap being formed between the collector layer and the insulating film, and further including a base layer and an emitter layer disposed over the collector layer, and a manufacturing method of the semiconductor device. Since the collector layer has a shape extending in a portion thereof in the upward direction and the horizontal direction, an external collector region can be deleted, and both the parasitic capacitance and the collector capacitance in the intrinsic portion attributable to the collector can be decreased and, accordingly, a bipolar transistor capable of high speed operation at a reduced consumption power can be constituted.

Abstract: In a semiconductor multi-layer structure in which a first SiGe layer having a first conductivity-type and high impurity concentration, a second SiGe layer having the first conductivity-type and a low impurity concentration and a Si layer having a low impurity concentration are formed one on another in this order on a Si substrate of the first conductivity-type, a channel is formed in a part of the Si layer and a source electrode passes through the second SiGe layer of low impurity concentration to electrically contact the first SiGe layer of high impurity concentration or the substrate.

Abstract: A bipolar type semiconductor device capable of attaining high current gain and high cut-off frequency and performing a satisfactory transistor operation also in a high current region while maintaining a high breakdown voltage performance, as well as a method of manufacturing the semiconductor device, are provided. In a collector comprising a first semiconductor layer and a second semiconductor layer narrower in band gap than the first semiconductor layer, an impurity is doped so as to have a peak of impurity concentration within the second collector layer and so that the value of the peak is higher than the impurity concentration at any position within the first collector layer. It is preferable to adjust the concentration of the doped impurity in such a manner that a collector-base depletion layer extends up to the first collector layer.

Abstract: A semiconductor device having an MODFET and at least one other device formed on one identical semiconductor substrate, in which an intrinsic region for the MODFET is formed by selective growth in a groove formed on a semiconductor substrate having an insulation film on the side wall of the groove, and single-crystal silicon at the bottom of the groove, is disclosed. The step between the MODFET and the at least one other device mounted together on one identical substrate can be thereby decreased, and each of the devices can be reduced in the size and integrated to a high degree, and the interconnection length can be shortened to reduce power consumption.

Abstract: The purpose of this invention is to realize a radio frequency monolithic integrated circuit high in performance, small in size and low in cost, where transistors and passive elements are arranged on a chip in which a conductive silicon substrate functions as a ground. Since the electromagnetic fields of passive elements induce a current in a conductive silicon substrate, a loss due to generation of Joule heat or the like occurs to lead to deterioration of the performance of the passive elements. To solve this problem, an SOI layer comprising a semiconductor layer having a large thickness and a high resistivity and a conductive silicon substrate is used, and passive elements and an active element are formed on the same substrate. Alternatively, a cavity is provided in the conductive substrate directly beneath the SOI layer in the region where the passive elements are formed, thereby attaining the object.

Abstract: A bipolar transistor is provided which is of high reliability and high gain, and which is particularly suitable to high speed operation. The bipolar transistor operates with high accuracy and with no substantial change of collector current even upon change of collector voltage. It also has less variation than conventional bipolar transistors for the collector current while ensuring high speed properties and high gain. In one example, the band gap in the base region is smaller than the band gap in the emitter and collector regions. The band gap is constant near the junction with the emitter region and decreases toward the junction with the collector region. A single crystal silicon/germanium is a typically used for the base region.