A nitride semiconductor device includes a channel layer, a barrier layer made of Al.sub.xIn.sub.yGa.sub.1-x-yN (x>0, x+y1), an active region that has a layered structure including the channel layer and the barrier layer, an inactive region that is formed at the layered structure around the active region and that is a concave portion having a bottom portion that reaches the channel layer, a gate layer made of a nitride semiconductor selectively formed on the barrier layer in the active region, a gate electrode formed on the gate layer, a first insulating film that covers the gate electrode and that is in contact with the barrier layer in the active region, and a second insulating film that covers the first insulating film and that is in contact with the inactive region.

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 semiconductor device includes a GaN FET on a silicon substrate and a buffer layer of III-N semiconductor material, with a columnar region, a transition region surrounding the columnar region, and an inter-columnar region around the transition region. The columnar region is higher than the inter-columnar region. The GaN FET includes a gate of III-N semiconductor material with a thickness greater than twice the vertical range of the top surface of the buffer layer in the columnar region. A difference between the gate thickness over the columnar region and over the transition region is less than half of the vertical range of the top surface of the buffer layer in the columnar surface. The semiconductor device may be formed by forming a gate layer of III-N semiconductor material over the barrier layer by a gate MOVPE process using a carrier gas that includes zero to 40 percent hydrogen gas.

The transistor includes a first III-V compound layer. A second III-V compound layer is disposed on the first III-V compound layer and is different from the first III-V compound layer in composition. A carrier channel is located between the first III-V compound layer and the second III-V compound layer. A source feature and a drain feature are disposed on the second III-V compound layer.

Apparatus and circuits with dual threshold voltage transistors and methods of fabricating the same are disclosed. In one example, a semiconductor structure is disclosed. The semiconductor structure includes: a substrate; a first layer comprising a first III-V semiconductor material formed over the substrate; a first transistor formed over the first layer, and a second transistor formed over the first layer. The first transistor comprises a first gate structure comprising a first material, a first source region and a first drain region. The second transistor comprises a second gate structure comprising a second material, a second source region and a second drain region. The first material is different from the second material.

A high-electron-mobility transistor comprises a semiconductor body comprising a barrier region and a channel region that forms a heterojunction with the barrier region such that a two-dimensional charge carrier gas channel is disposed in the channel region, source and drain electrodes disposed on the semiconductor body and laterally spaced apart from one another, a gate structure disposed on the semiconductor body and laterally between the source and drain electrodes, the gate structure being configured to control a conduction state of two-dimensional charge carrier gas, and a first dielectric region that is disposed along the upper surface of the semiconductor body in a lateral region that is between the gate structure and the drain electrode, wherein the first dielectric region comprises aluminum and oxide, and wherein first dielectric region comprises a first end that faces and is laterally spaced apart from the gate structure.

A high electron mobility transistor and a method of manufacturing the same are disclosed. The high electron mobility transistor includes a channel layer, a channel supplying layer causing generation of a two-dimensional electron gas (2DEG) in the channel layer, a source electrode and a drain electrode provided on respective sides of the channel supplying layer, a depletion forming layer provided on the channel supplying layer to form a depletion region in the 2DEG, a gate electrode provided on a portion of the depletion forming layer, and a current limiting layer provided to contact the gate electrode on another portion of the depletion forming layer. The current limiting layer limits a current flow from the gate electrode to the depletion forming layer according to a voltage applied to the gate electrode.

A method includes: providing a Group III nitride-based substrate having a first major surface and a doped Group III nitride region; forming a first passivation layer configured as a hydrogen diffusion barrier on the first major surface; forming a first opening in the first passivation layer and exposing at least a portion of the doped Group III nitride region from the first passivation layer; activating a first doped Group III nitride region whilst the first passivation layer is located on the first major surface and the doped Group III nitride region is at least partly exposed from the first passivation layer; forming a second passivation layer on the first passivation layer and on the doped Group III nitride region; forming a second opening in the first and second passivation layers and exposing a portion of the doped Group III nitride region; and forming a contact in the second opening.

A junction field effect transistor device includes a substrate, a well region, a first top layer, a plurality of source/drain regions, a first isolation structure, a gate, and a plurality of first well slots. The substrate has a first conductivity type. The well region is embedded in the substrate. The well region has a second conductivity type. The first top layer is embedded in the well region. The first top layer has the first conductivity type. The source/drain regions are disposed on a top surface of the well region. The first isolation structure is adjacent to one of the source/drain regions. The gate is disposed on a top surface of the first top layer. The first well slots are disposed below the gate. A second-conductivity-type dopant concentration of the first well slots is lower than a second-conductivity-type dopant concentration of the well region.

A method for manufacturing nitride semiconductor device includes a second step of forming, on a gate layer material film, a gate electrode film that is a material film of a gate electrode, a third step of selectively etching the gate electrode film to form the gate electrode 22 of a ridge shape, and a fourth step of selectively etching the gate layer material film to form a semiconductor gate layer 21 of a ridge shape with the gate electrode 22 disposed at a width intermediate portion of a front surface thereof. The third step includes a first etching step for forming a first portion 22A from an upper end to a thickness direction intermediate portion of the gate electrode 22 and a second etching step being a step differing in etching condition from the first etching step and being for forming a remaining second portion 22B of the gate electrode.