According to one embodiment, a semiconductor device includes first to third electrodes, first and second semiconductor regions, and a first member. The first semiconductor region includes Al.sub.x1Ga.sub.1-x1N (0≤x1<1). The second semiconductor region includes Al.sub.x2Ga.sub.1-x2N (x1<x2≤1). The first member includes first and second regions. The second region is between the first region and the first electrode region of the second electrode. A part of the second region is between the second semiconductor portion of the second semiconductor region and the second electrode region. The second region includes at least one first element selected from the group consisting of Ti, Al, Ga, Ni, Nb, Mo, Ta, Hf, V, and Au. The first region does not include the first element, or a concentration of the first element in the first region is lower than a concentration of the first element in the second region.

A semiconductor device includes a substrate, a first semiconductor layer formed over the substrate, a second semiconductor layer formed over the first semiconductor layer, a third semiconductor layer formed over the second semiconductor layer, and a gate electrode, a source electrode, and a drain electrode that are formed over the third semiconductor layer. The first semiconductor layer includes a first nitride semiconductor. The second semiconductor includes a second nitride semiconductor. The third semiconductor layer includes a third nitride semiconductor. The concentration of oxygen included in the second semiconductor layer is less than 5.0×10.sup.18 cm.sup.−3. The concentration of oxygen included in the third semiconductor layer is greater than or equal to 5.0×10.sup.18 cm.sup.−3.

A transistor device includes a compound semiconductor body, a drain disposed in the compound semiconductor body and a source disposed in the compound semiconductor body and spaced apart from the drain by a channel region. A gate is provided for controlling the channel region. The transistor device further includes a gate overvoltage protection device connected between the source and the gate, the gate overvoltage protection device including p-type and n-type silicon-containing semiconductor material.

A first regrowth layer and a second regrowth layer comprising GaAs having high resistance are regrown on a surface of an etching stop layer exposed to the bottom of a first groove and a second groove, and then n-type InGaAs is regrown on the first regrowth layer and the second regrowth layer, whereby a source region and a drain region configured to make contact with a channel layer are formed in the first groove and the second groove respectively.

Gallium nitride high-electron-mobility transistors (GaN HEMTs) are at a point of rapid growth in defense (radar, SATCOM) and commercial (5G and beyond) industries. This growth also comes at a point at which the standard GaN heterostructures remain unoptimized for maximum performance. For this reason, the shift to the aluminum nitride (AlN) platform is disclosed. AlN allows for smarter, highly-scaled heterostructure design that improves the output power and thermal management of GaN amplifiers. Beyond improvements over the incumbent amplifier technology, AlN allows for a level of integration previously unachievable with GaN electronics. State-of-the-art high-current p-channel FETs, mature filter technology, and advanced waveguides, all monolithically integrated with an AlN/GaN/AlN HEMT, is made possible with aluminum nitride. It is on this AlN platform that nitride electronics may maximize their full high-power, highspeed potential for mm-wave communication and high-power logic applications.

A HEMT transistor has a semiconductor layer structure that comprises a Group III nitride-based channel layer and a higher bandgap Group III nitride-based barrier layer on the channel layer. A gate finger and first and second source/drain contacts are provided on the semiconductor layer structure. A first source/drain region is provided in the semiconductor layer structure that includes a first implanted region that is underneath the first source/drain contact and a first auxiliary implanted region. A depth of the first implanted region is at least twice a depth of the first auxiliary implanted a region. The first source/drain region extends inwardly a first distance from a lower edge of an inner sidewall of the first source/drain contact, and extends outwardly a second smaller distance from a lower edge of an outer sidewall of the first source/drain contact.

A method of forming an alignment contact includes: providing a III-nitride substrate; epitaxially growing a first III-nitride layer on the III-nitride substrate, wherein the first III-nitride layer is characterized by a first conductivity type; forming a plurality of III-nitride fins on the first III-nitride layer, wherein each the plurality of III-nitride fins is separated by one of a plurality of first recess regions, wherein the plurality of III-nitride fins are characterized by the first conductivity type; epitaxially regrowing a III-nitride source contact portion on each of the plurality of III-nitride fins; and forming a source contact structure on the III-nitride source contact portions.

In some examples, a transistor comprises a gallium nitride (GaN) layer; a GaN-based alloy layer having a top side and disposed on the GaN layer, wherein source, drain, and gate contact structures are supported by the GaN layer; and a first doped region positioned in a drain access region and extending from the top side into the GaN layer.

In some examples, a transistor comprises a gallium nitride (GaN) layer; a GaN-based alloy layer having a top side and disposed on the GaN layer, wherein source, drain, and gate contact structures are supported by the GaN layer; and a first doped region positioned in a drain access region and extending from the top side into the GaN layer.

A vertical insulated-gate field effect transistor includes a semiconductor substrate and a gate electrode on a first surface thereof. This gate electrode has a plurality of eight (or more) sided openings extending therethrough. Each of these openings has eight (or more) sidewalls, including a first plurality of sidewalls that are flat relative to a center of the opening and second plurality of sidewalls that are either flat or concave relative to the center of the opening. A source electrode is also provided, which extends into the openings. This source electrode may ohmically contact a source region within the semiconductor substrate. If the field effect transistor is a JBSFET, the source electrode may also form a Schottky rectifying junction with a drift region within the semiconductor substrate.