Abstract: A semiconductor device is provided with one or more gate fingers (20) that are provided in an active region on a semiconductor substrate (1), and a source finger (30) and a drain finger (40) that are provided in the active region and arranged alternately to allow each gate finger to be sandwiched between the source and drain fingers. The semiconductor device includes terminal circuit (60) that has inductive impedance at the frequency of a signal input to an input terminal of the one or more gate fingers, and is directly or indirectly connected to the one or more gate fingers at an area being spaced away from a connecting position of the input terminal (21a) of the one or more gate fingers (20).

Abstract: A semiconductor device is provided with one or more gate fingers (20) that are provided in an active region on a semiconductor substrate (1), and a source finger (30) and a drain finger (40) that are provided in the active region and arranged alternately to allow each gate finger to be sandwiched between the source and drain fingers. The semiconductor device includes terminal circuit (60) that has inductive impedance at the frequency of a signal input to an input terminal of the one or more gate fingers, and is directly or indirectly connected to the one or more gate fingers at an area being spaced away from a connecting position of the input terminal (21a) of the one or more gate fingers (20).

Abstract: A power amplifier includes: an amplifier; an input matching circuit connected to an input of the amplifier; an output matching circuit connected to an output of the amplifier; and a low-frequency processing circuit connected to the input matching circuit or the output matching circuit, wherein the low-frequency processing circuit includes a first line having a first end connected to the input matching circuit or the output matching circuit, a first shot stub connected to a second end of the first line and including a second line and a first capacitor connected in series each other, and a second short stub connected to the second end of the first line in parallel with the first short stub and including a third line and a second capacitor which are connected in series each other, the first line has a length of ?/8, the second line has a length of ?/4, and the third line has a length of ?/8 with respect to a wavelength ? of a fundamental frequency.

Abstract: A power amplifier includes: an amplifier; an input matching circuit connected to an input of the amplifier; an output matching circuit connected to an output of the amplifier; and a low-frequency processing circuit connected to the input matching circuit or the output matching circuit, wherein the low-frequency processing circuit includes a first line having a first end connected to the input matching circuit or the output matching circuit, a first shot stub connected to a second end of the first line and including a second line and a first capacitor connected in series each other, and a second short stub connected to the second end of the first line in parallel with the first short stub and including a third line and a second capacitor which are connected in series each other, the first line has a length of ?/8, the second line has a length of ?/4, and the third line has a length of ?/8 with respect to a wavelength ? of a fundamental frequency.

Abstract: A semiconductor device includes a substrate, a buffer layer of GaN containing at least one of Fe and C and disposed on the substrate, a channel layer of GaN disposed on the buffer layer and through which electrons travel, an electron supply layer disposed on the channel layer and producing a two-dimensional electron gas in the channel layer, a gate electrode, a drain electrode, and a source electrode. Recovery time of a drain current of the semiconductor device is no more than 5 seconds, where the recovery time is defined as the period of time after the semiconductor device is stopped from outputting high frequency power until the change in the drain current, after the stopping of the semiconductor device, reaches 95% of the change in the drain current occurring during the first 10 seconds after the stopping of the semiconductor device.

Abstract: A semiconductor device includes a substrate, a buffer layer of GaN containing at least one of Fe and C and disposed on the substrate, a channel layer of GaN disposed on the buffer layer and through which electrons travel, an electron supply layer disposed on the channel layer and producing a two-dimensional electron gas in the channel layer, a gate electrode, a drain electrode, and a source electrode. Recovery time of a drain current of the semiconductor device is no more than 5 seconds, where the recovery time is defined as the period of time after the semiconductor device is stopped from outputting high frequency power until the change in the drain current, after the stopping of the semiconductor device, reaches 95% of the change in the drain current occurring during the first 10 seconds after the stopping of the semiconductor device.

Abstract: A semiconductor device includes: a package; an input matching circuit and an output matching circuit in the package; and transistor chips between the input matching circuit and the output matching circuit in the package. Each transistor chip includes a semiconductor substrate having long sides and short sides that are shorter than the long sides, and a gate electrode, a drain electrode and a source electrode on the semiconductor substrate. The gate electrode has gate fingers arranged along the long sides of the semiconductor substrate and a gate pad commonly connected to the gate fingers and connected to the input matching circuit via a first wire. The drain electrode is connected to the output matching circuit via a second wire. The long sides of the semiconductor substrates of the transistor chips are oblique with respect to an input/output direction extending from the input matching circuit to the output matching circuit.

Abstract: A semiconductor device includes: a package; an input matching circuit and an output matching circuit in the package; and transistor chips between the input matching circuit and the output matching circuit in the package. Each transistor chip includes a semiconductor substrate having long sides and short sides that are shorter than the long sides, and a gate electrode, a drain electrode and a source electrode on the semiconductor substrate. The gate electrode has gate fingers arranged along the long sides of the semiconductor substrate and a gate pad commonly connected to the gate fingers and connected to the input matching circuit via a first wire. The drain electrode is connected to the output matching circuit via a second wire. The long sides of the semiconductor substrates of the transistor chips are oblique with respect to an input/output direction extending from the input matching circuit to the output matching circuit.

Abstract: A semiconductor device includes: a semiconductor substrate; an impurity-doped region at a top surface of the semiconductor substrate; an insulating region located around the impurity-doped region on the top surface of the semiconductor substrate; a gate electrode on the impurity-doped region; a first electrode and a second electrode located on the impurity-doped region, sandwiching the gate electrode; a first pad located on the insulating region and connected to the gate electrode; a second pad facing the first pad across the impurity-doped region, on the insulating region, and connected to the second electrode; and a conductor located between the first electrode and the second pad on the insulating region.

Abstract: A semiconductor device includes: a semiconductor substrate; an impurity-doped region at a top surface of the semiconductor substrate; an insulating region located around the impurity-doped region on the top surface of the semiconductor substrate; a gate electrode on the impurity-doped region; a first electrode and a second electrode located on the impurity-doped region, sandwiching the gate electrode; a first pad located on the insulating region and connected to the gate electrode; a second pad facing the first pad across the impurity-doped region, on the insulating region, and connected to the second electrode; and a conductor located between the first electrode and the second pad on the insulating region.

Abstract: A field-effect transistor includes a channel layer formed of a III-V compound semiconductor excluding aluminum; a gate contact layer formed of a III-V compound semiconductor and provided on the channel layer, the III-V compound semiconductor having a dopant concentration equal to or less than 1×1016 cm?3, containing aluminum, and having a large band gap energy; a gate buried layer of a III-V compound semiconductor and provided on the gate contact layer; and a gate electrode buried in the gate buried layer and in contact with the gate contact layer. A recess in the gate buried layer is opposed to an upper side wall of the gate electrode with a gap therebetween and a part of the gate buried layer, and where a contact with a lower side wall of the gate electrode is established, part of the gate buried layer remains without being removed.

Abstract: A semiconductor device includes a substrate having a recess, a gate electrode in the recess in the substrate, and a source electrode and a drain electrode disposed on opposite sides of the gate electrode. An insulating film is on at least on a surface of the gate electrode and a portion in the recess, other than where the gate electrode is located, and a shield electrode connected to the source electrode is located on a portion of the insulating film between the gate electrode and the drain electrode.

Abstract: A high-frequency power amplifier has an FET element having a unit FETs in multifinger form, and having a gate pad through which a signal is input, a source pad that is grounded, and a drain pad through which a signal is output. A high-frequency processing circuit includes series resonance circuits shunt-connected between the gate pads of the unit FETs and grounding ends. Two of the series resonance circuits have respective different resonance frequencies which correspond to second and higher harmonics of a frequency included in the operating frequency band of the FET element.

Abstract: A high-frequency power amplifier has an FET element having a unit FETs in multifinger form, and having a gate pad through which a signal is input, a source pad that is grounded, and a drain pad through which a signal is output. A high-frequency processing circuit includes series resonance circuits shunt-connected between the gate pads of the unit FETs and grounding ends. Two of the series resonance circuits have respective different resonance frequencies which correspond to second and higher harmonics of a frequency included in the operating frequency band of the FET element.

Abstract: A field effect transistor includes a semiconductor substrate having an active region, a source region, and a drain region at an upper portion of the substrate. The active region is located between the source and drain regions. A gate electrode is located on the active region. A source electrode is located on the source region and forms an ohmic contact with the source region. A drain electrode has a base part on and in ohmic contact with the drain region and an extended part having edge close to the gate electrode and over a boundary between the active region and the drain region. An insulating film is located between the boundary and the extended part and has a thickness that increases along a direction from the drain electrode toward the gate electrode in a step-by-step or continuous manner.

Abstract: A field-effect transistor includes a channel layer formed of a III-V compound semiconductor excluding aluminum; a gate contact layer formed of a III-V compound semiconductor and provided on the channel layer, the III-V compound semiconductor having a dopant concentration equal to or less than 1×1016 cm?3, containing aluminum, and having a large band gap energy; a gate buried layer of a III-V compound semiconductor and provided on the gate contact layer; and a gate electrode buried in the gate buried layer and in contact with the gate contact layer. A recess in the gate buried layer is opposed to an upper side wall of the gate electrode with a gap therebetween and a part of the gate buried layer, and where a contact with a lower side wall of the gate electrode is established, part of the gate buried layer remains without being removed.

Abstract: A semiconductor device operating at a frequency between 0.8 GHz and 300 GHz includes an active region that is positioned on a semi-insulating GaAs substrate; a gate electrode that is positioned in the active region; and a source electrode and a drain electrode that are positioned on the surface of the active region facing each other with the gate electrode positioned between the source electrode and the drain electrode. A drain side active region, which is a part of the active region and positioned between the gate electrode and the drain electrode, increases in width in the direction to the drain electrode from the gate electrode.

Abstract: A semiconductor device includes a substrate having a recess, a gate electrode in the recess in the substrate, and a source electrode and a drain electrode disposed on opposite sides of the gate electrode. An insulating film is on at least on a surface of the gate electrode and a portion in the recess, other than where the gate electrode is located, and a shield electrode connected to the source electrode is located on a portion of the insulating film between the gate electrode and the drain electrode.

Abstract: A gate electrode serving as a Schottky electrode includes a TaNx layer and an Au layer. The TaNx layer serves as a barrier metal for preventing atoms from diffusing from the Au layer into a substrate. TaNx does not contain Si, and therefore has a higher humidity resistance than WSiN containing Si. Accordingly, the gate electrode has a higher humidity resistance than a conventional gate electrode including a WSiN layer. Setting a nitrogen content at less than 0.8 can prevent significant degradation in Schottky characteristics as compared to the conventional gate electrode. Setting the nitrogen content at 0.5 or less, Schottky characteristics can be improved more than in the conventional gate electrode.

Abstract: A semiconductor device includes a semiconductor substrate having a principal plane on which gate, source, and drain electrodes are located. A film made of a polymer with a low dielectric constant is over the gate and drain electrodes to insulate the gate and drain electrodes from the source electrodes. A chip surface electrode located over the low-dielectric-constant polymer film and the source electrode, and connected to ground potential. The source electrode is provided with the ground potential through the chip surface electrode.