Abstract: A semiconductor device has: a semiconductor substrate having a pair of current input/output regions via which current flows; an insulating film formed on the semiconductor substrate and having a gate electrode opening; and a mushroom gate electrode structure formed on the semiconductor substrate via the gate electrode opening, the mushroom gate electrode structure having a stem and a head formed on the stem, the stem having a limited size on the semiconductor substrate along a current direction and having a forward taper shape upwardly and monotonically increasing the size along the current direction, the head having a size expanded stepwise along the current direction, and the stem contacting the semiconductor substrate in the gate electrode opening and riding the insulating film near at a position of at least one of opposite ends of the stem along the current direction.

Abstract: A semiconductor device has: a semiconductor substrate having a pair of current input/output regions via which current flows; an insulating film formed on the semiconductor substrate and having a gate electrode opening; and a mushroom gate electrode structure formed on the semiconductor substrate via the gate electrode opening, the mushroom gate electrode structure having a stem and a head formed on the stem, the stem having a limited size on the semiconductor substrate along a current direction and having a forward taper shape upwardly and monotonically increasing the size along the current direction, the head having a size expanded stepwise along the current direction, and the stem contacting the semiconductor substrate in the gate electrode opening and riding the insulating film near at a position of at least one of opposite ends of the stem along the current direction.

Abstract: A process of manufacturing a semiconductor device includes the steps of forming a stacked structure of a first III-V compound semiconductor layer containing In and having a composition different from InP and a second III-V compound semiconductor layer containing In. The second III-V compound semiconductor layer is formed over the first III-V compound semiconductor layer and growing an InP layer at regions adjacent the stacked structure to form a stepped structure of InP. The process further includes the step of wet-etching the stepped structure and the second III-V compound semiconductor layer using an etchant containing hydrochloric acid and acetic acid to remove at least the second III-V compound semiconductor layer.

Abstract: A semiconductor device has: a semiconductor substrate having a pair of current input/output regions via which current flows; an insulating film formed on the semiconductor substrate and having a gate electrode opening; and a mushroom gate electrode structure formed on the semiconductor substrate via the gate electrode opening, the mushroom gate electrode structure having a stem and a head formed on the stem, the stem having a limited size on the semiconductor substrate along a current direction and having a forward taper shape upwardly and monotonically increasing the size along the current direction, the head having a size expanded stepwise along the current direction, and the stem contacting the semiconductor substrate in the gate electrode opening and riding the insulating film near at a position of at least one of opposite ends of the stem along the current direction.

Abstract: A semiconductor device has: a semiconductor substrate having a pair of current input/output regions via which current flows; an insulating film formed on the semiconductor substrate and having a gate electrode opening; and a mushroom gate electrode structure formed on the semiconductor substrate via the gate electrode opening, the mushroom gate electrode structure having a stem and a head formed on the stem, the stem having a limited size on the semiconductor substrate along a current direction and having a forward taper shape upwardly and monotonically increasing the size along the current direction, the head having a size expanded stepwise along the current direction, and the stem contacting the semiconductor substrate in the gate electrode opening and riding the insulating film near at a position of at least one of opposite ends of the stem along the current direction.

Abstract: A semiconductor device has: a semiconductor substrate having a pair of current input/output regions via which current flows; an insulating film formed on the semiconductor substrate and having a gate electrode opening; and a mushroom gate electrode structure formed on the semiconductor substrate via the gate electrode opening, the mushroom gate electrode structure having a stem and a head formed on the stem, the stem having a limited size on the semiconductor substrate along a current direction and having a forward taper shape upwardly and monotonically increasing the size along the current direction, the head having a size expanded stepwise along the current direction, and the stem contacting the semiconductor substrate in the gate electrode opening and riding the insulating film near at a position of at least one of opposite ends of the stem along the current direction.

Abstract: A switching circuit includes switching transistors connected to one of an input terminal and an output terminal of the switching circuit, and a control bias supply circuit that supplies a control bias for cutting off all the switching transistors to the switching transistors when all of the switching transistors are in a non-selected state.

Abstract: Transmitter and receiver for wireless communications with improved accuracy and stability in radio frequency control. A transmitter mixes an information-carrying signal (first signal) and a non-modulated wave signal (second signal) with a carrier signal, thereby producing a first and second radio frequency signals for radio wave transmission. A receiver mixes those two radio frequency signals to extract the original information signal. While the received radio frequency signals contain some frequency fluctuations and phase noises that have been introduced at the sending end, such unstable components ?f will cancel out at the receiving end.

Abstract: A switching circuit includes switching transistors connected to one of an input terminal and an output terminal of the switching circuit, and a control bias supply circuit that supplies a control bias for cutting off all the switching transistors to the switching transistors when all of the switching transistors are in a non-selected state.

Abstract: A semiconductor device has: a semiconductor substrate having a pair of current input/output regions via which current flows; an insulating film formed on the semiconductor substrate and having a gate electrode opening; and a mushroom gate electrode structure formed on the semiconductor substrate via the gate electrode opening, the mushroom gate electrode structure having a stem and a head formed on the stem, the stem having a limited size on the semiconductor substrate along a current direction and having a forward taper shape upwardly and monotonically increasing the size along the current direction, the head having a size expanded stepwise along the current direction, and the stem contacting the semiconductor substrate in the gate electrode opening and riding the insulating film near at a position of at least one of opposite ends of the stem along the current direction.

Abstract: A semiconductor light-receiving device includes: a semi-insulating substrate; a semiconductor layer of a first conduction type that is formed on the semi-insulating substrate; a buffer layer of the first conduction type that is formed on the semi-insulating substrate and has a lower impurity concentration than the semiconductor layer of the first conduction type; a light absorption layer that is formed on the buffer layer and generates carriers in accordance with incident light; a semiconductor layer of a second conduction type that is formed on the light absorption layer; and a semiconductor intermediate layer that is interposed between the buffer layer and the light absorption layer, and has a forbidden bandwidth within a range lying between the forbidden bandwidth of the buffer layer and the forbidden bandwidth of the light absorption layer.

Abstract: A switching circuit includes switching transistors connected to one of an input terminal and an output terminal of the switching circuit, and a control bias supply circuit that supplies a control bias for cutting off all the switching transistors to the switching transistors when all of the switching transistors are in a non-selected state.

Abstract: A process of manufacturing a semiconductor device includes the steps of forming a stacked structure of a first III-V compound semiconductor layer containing In and having a composition different from InP and a second III-V compound semiconductor layer containing In. The second III-V compound semiconductor layer is formed over the first III-V compound semiconductor layer and growing an InP layer at regions adjacent the stacked structure to form a stepped structure of InP. The process further includes the step of wet-etching the stepped structure and the second III-V compound semiconductor layer using an etchant containing hydrochloric acid and acetic acid to remove at least the second III-V compound semiconductor layer.

Abstract: A semiconductor device has: a semiconductor substrate having a pair of current input/output regions via which current flows; an insulating film formed on the semiconductor substrate and having a gate electrode opening; and a mushroom gate electrode structure formed on the semiconductor substrate via the gate electrode opening, the mushroom gate electrode structure having a stem and a head formed on the stem, the stem having a limited size on the semiconductor substrate along a current direction and having a forward taper shape upwardly and monotonically increasing the size along the current direction, the head having a size expanded stepwise along the current direction, and the stem contacting the semiconductor substrate in the gate electrode opening and riding the insulating film near at a position of at least one of opposite ends of the stem along the current direction.

Abstract: A process of manufacturing a semiconductor device includes the steps of forming a stacked structure of a first III-V compound semiconductor layer containing In and having a composition different from InP and a second III-V compound semiconductor layer containing In. The second III-V compound semiconductor layer is formed over the first III-V compound semiconductor layer and growing an InP layer at regions adjacent the stacked structure to form a stepped structure of InP. The process further includes the step of wet-etching the stepped structure and the second III-V compound semiconductor layer using an etchant containing hydrochloric acid and acetic acid to remove at least the second III-V compound semiconductor layer.

Abstract: An optical multilayer film includes: a first layer; a second layer that contains titanium oxynitride as a main component; and a third layer that contains magnesium fluoride as a main component; the first layer that has a different refractive index from that of the second layer or the third layer; and the first layer, the second layer, and the third layer being part of a laminated structure that includes a plurality of reflection planes. The thickness of the third layer is smaller than ¼ wavelength.

Abstract: A switch device includes a semiconductor chip, and at least two switches formed on the semiconductor chip. Ground parts of the at least two switches are arranged between said at least two switches.

Abstract: A semiconductor device has: a semiconductor substrate having a pair of current input/output regions via which current flows; an insulating film formed on the semiconductor substrate and having a gate electrode opening; and a mushroom gate electrode structure formed on the semiconductor substrate via the gate electrode opening, the mushroom gate electrode structure having a stem and a head formed on the stem, the stem having a limited size on the semiconductor substrate along a current direction and having a forward taper shape upwardly and monotonically increasing the size along the current direction, the head having a size expanded stepwise along the current direction, and the stem contacting the semiconductor substrate in the gate electrode opening and riding the insulating film near at a position of at least one of opposite ends of the stem along the current direction.

Abstract: A semiconductor device has: a semiconductor substrate having a pair of current input/output regions via which current flows; an insulating film formed on the semiconductor substrate and having a gate electrode opening; and a mushroom gate electrode structure formed on the semiconductor substrate via the gate electrode opening, the mushroom gate electrode structure having a stem and a head formed on the stem, the stem having a limited size on the semiconductor substrate along a current direction and having a forward taper shape upwardly and monotonically increasing the size along the current direction, the head having a size expanded stepwise along the current direction, and the stem contacting the semiconductor substrate in the gate electrode opening and riding the insulating film near at a position of at least one of opposite ends of the stem along the current direction.

Abstract: A field-effect transistor includes a channel layer that is formed on a predetermined semiconductor layer and has an impurity concentration varying from a low value to a high value, and a source region and a drain region each having a bottom face above the predetermined semiconductor layer.