A nitride semiconductor device includes a SiC substrate having a hexagonal crystal structure and including a main surface inclined with respect to a c-plane at an off-angle from 2 to 6 in a specific crystal direction, a nitride semiconductor layer located on the main surface of the SiC substrate and including an electron transit layer and an electron supply layer, and a gate electrode, a source electrode, and a drain electrode located on the nitride semiconductor layer. The main surface is parallel to a first direction, a second direction orthogonal to the first direction, and a third direction coinciding with the specific crystal direction in plan view. The source electrode and the drain electrode are separated in the first direction. The gate electrode extends in the second direction between the source electrode and the drain electrode. The first direction intersects the third direction at an angle of 9015.

A nitride semiconductor device 1 includes a first nitride semiconductor layer 4 that constitutes an electron transit layer, a second nitride semiconductor layer 5 that is formed on the first nitride semiconductor layer, is larger in bandgap than the first nitride semiconductor layer, and constitutes an electron supply layer, and a gate portion 20 that is formed on the second nitride semiconductor layer. The gate portion 20 includes a first semiconductor gate layer 21 of a ridge shape that is disposed on the second nitride semiconductor layer 5 and is constituted of a nitride semiconductor containing an acceptor type impurity, a second semiconductor gate layer 22 that is formed on the first semiconductor gate layer 21 and is constituted of a nitride semiconductor with a larger bandgap than the first semiconductor gate layer 21, and a gate electrode 23 that is formed on the second semiconductor gate layer 22 and is in Schottky junction with the second semiconductor gate layer 22.

A semiconductor device including: a first silicon level including a first single crystal silicon layer and a plurality of first transistors; a first metal layer disposed over the first silicon level; a second metal layer disposed over the first metal layer; a third metal layer disposed over the second metal layer; a second level including a plurality of second transistors, disposed over the third metal layer; a third level including a plurality of third transistors, disposed over the second level; a via disposed through the second and third levels; a fourth metal layer disposed over the third level; a fifth metal layer disposed over the fourth metal layer; and a fourth level including a second single crystal silicon layer and is disposed over the fifth metal layer, where each of the plurality of second transistors includes a metal gate, and the via has a diameter of less than 450 nm.

In an embodiment, a Group III nitride-based transistor device is provided that includes a Group III nitride-based body and a p-type Schottky gate including a metal gate on a p-doped Group III nitride structure. The p-doped Group III nitride structure includes an upper p-doped GaN layer in contact with the metal gate and having a thickness d.sub.1, a lower p-doped Group III nitride layer having a thickness d.sub.2 and including p-doped GaN that is arranged on and in contact with the Group III nitride-based body, and at least one p-doped Al.sub.xGa.sub.1-xN layer arranged between the upper p-doped GaN layer and the lower p-doped Group III nitride layer, wherein 0<x<1. The thickness d.sub.2 of the lower p-doped Group III nitride layer is larger than the thickness d.sub.1 of the upper p-doped GaN layer.

A gate electrode includes a main portion formed of a gate electrode material, and a gate electrode barrier layer disposed between the main portion and a barrier layer and formed of a conductive material that prevents the gate electrode material from diffusing into the barrier layer. A surface of the main portion in a region above a first insulating layer faces a periphery without a layer of the conductive material being formed.

A gate electrode includes a main portion formed of a gate electrode material, and a gate electrode barrier layer disposed between the main portion and a barrier layer and formed of a conductive material that prevents the gate electrode material from diffusing into the barrier layer. A surface of the main portion in a region above a first insulating layer faces a periphery without a layer of the conductive material being formed.

A power amplifier module includes a power amplifier including a GaAs bipolar transistor having a collector, a base abutting the collector, and an emitter, the collector having a doping concentration of at least about 310.sup.16 cm.sup.3 at a junction with the base, the collector also having at least a first grading in which doping concentration increases away from the base; and an RF transmission line driven by the power amplifier, the RF transmission line including a conductive layer and finish plating on the conductive layer, the finish plating including a gold layer, a palladium layer proximate the gold layer, and a diffusion barrier layer proximate the palladium layer, the diffusion barrier layer including nickel and having a thickness that is less than about the skin depth of nickel at 0.9 GHZ. Other embodiments of the module are provided along with related methods and components thereof.

A semiconductor structure includes a heterojunction bipolar transistor (HBT) including a collector layer located over a substrate, the collector layer including a semiconductor material, and a field effect transistor (FET) located over the substrate, the FET having a channel formed in the semiconductor material that forms the collector layer of the HBT. In some implementations, a second FET can be provided so as to be located over the substrate and configured to include a channel formed in a semiconductor material that forms an emitter of the HBT. One or more of the foregoing features can be implemented in devices such as a die, a packaged module, and a wireless device.

A field effect transistor comprising a buffer and channel layer formed successively on a substrate. A source electrode, drain electrode, and gate are all formed in electrical contact with the channel layer, with the gate between the source and drain electrodes. A spacer layer is formed on at least a portion of a surface of the channel layer between the gate and drain electrode and a field plate is formed on the spacer layer isolated from the gate and channel layer. The spacer layer is electrically connected by at least one conductive path to the source electrode, wherein the field plate reduces the peak operating electric field in the device.

One aspect of this disclosure is a power amplifier module that includes a power amplifier configured to provide a radio frequency signal at an output, an output matching network coupled to the output of the power amplifier and configured to provide impedance matching at a fundamental frequency of the radio frequency signal, and a harmonic termination circuit coupled to the output of the power amplifier. The power amplifier is included on a power amplifier die. The output matching network can include a first circuit element electrically connected to an output of the power amplifier by way of a pad on a top surface of a conductive trace, in which the top surface has an unplated portion between the pad the power amplifier die. The harmonic termination circuit can include a second circuit element. The first and second circuit elements can have separate electrical connections to the power amplifier die. Other embodiments of the module are provided along with related methods and components thereof.