A field effect transistor comprising: a first semiconductor structure, the first semiconductor structure having a channel layer; a second semiconductor structure, the second semiconductor structure is arranged on the first semiconductor structure, and the second semiconductor structure is stacked in sequence from bottom to top with a Schottky layer, a first etch stop layer, a wide recess layer, an ohmic contact layer, and a narrow recess, a wide recess is opened in the ohmic contact layer, so that the upper surface of the wide recess layer forms a wide recess area and the upper surface of the Schottky layer forms a narrow recess area; at least one delta-doped layer, a gate metal contact, the gate metal contact is formed inside the wide recess a source metal contact; and a drain metal contact, and the drain metal contact is located on the other side of the gate metal contact.

A semiconductor device includes a type III-V semiconductor body having a main surface and a rear surface opposite the main surface. A barrier region is disposed beneath the main surface. A buffer region is disposed beneath the barrier region. A first two-dimensional charge carrier gas region forms near an interface between the barrier region and the buffer region. A second two-dimensional charge carrier gas region forms near an interface between the buffer region and the first back-barrier region. A third two-dimensional charge carrier gas region forms near an interface between the first back-barrier region and the second back-barrier region. Both of the second and third two-dimensional charge carrier gas regions have an opposite carrier type as the first two-dimensional charge carrier gas region. The third two-dimensional charge carrier gas region is more densely populated with charge carriers than the second two-dimensional charge carrier gas region.

An epitaxial structure includes a substrate, a buffer layer, a channel layer, an intermediate layer, and a barrier layer. The buffer layer is disposed on the substrate, the channel layer is disposed on the buffer layer, the barrier layer is disposed on the channel layer, and the intermediate layer is disposed between the channel layer and the barrier layer. The chemical composition of the barrier layer is Al.sub.x1In.sub.y1Ga.sub.z1N, and the chemical composition of the intermediate layer is Al.sub.x2In.sub.y2Ga.sub.z2N. The lattice constant of the barrier layer is greater than the lattice constant of the intermediate layer. The aluminum (Al) content of at least a portion of the intermediate layer is greater than the Al content of the barrier layer.

An epitaxial structure includes a substrate, a buffer layer, a channel layer, an intermediate layer, and a barrier layer. The buffer layer is disposed on the substrate, the channel layer is disposed on the buffer layer, the barrier layer is disposed on the channel layer, and the intermediate layer is disposed between the channel layer and the barrier layer. The chemical composition of the barrier layer is Al.sub.x1In.sub.y1Ga.sub.z1N, and the chemical composition of the intermediate layer is Al.sub.x2In.sub.y2Ga.sub.z2N. The lattice constant of the barrier layer is greater than the lattice constant of the intermediate layer. The aluminum (Al) content of at least a portion of the intermediate layer is greater than the Al content of the barrier layer.

The present invention is a FET having a p-doped or acceptor-doped layer underneath a FET channel to enable E/D Mode operation. A FET threshold voltage is tunable through a voltage applied to the p-doped layer via a metal contact such as a threshold-control terminal (TCT). The present invention has a dual E/D mode operation of a single FET device, and also a dual E/D mode operation with a single-polarity positive power supply voltage. The FET of the present invention is fabricated to enable dual enhancement-mode/depletion-mode (E-Mode/D-Mode) high electron mobility transistors (HEMTs), to enable dual E/D Mode operation by incorporating a p-doped or acceptor doped region underneath the channel, to achieve a tunable threshold voltage by varying the bias voltage on a fourth terminal called the threshold-control terminal (TCT) that contacts the p-doped layer, and to enable Dual E/D-Mode operation of a HEMT with a single-polarity positive power supply voltage.

A field effect transistor having a reduced sheet resistance is provided. A channel layer, a first spacer layer, a second spacer layer, a first electronic barrier layer, and a second electronic barrier layer are sequentially grown on the main surface of a substrate. A gate recess is created, and then an ion implanted section is formed. A third electronic barrier layer and a p-type layer are formed by a metalorganic chemical vapor deposition (MOCVD) method. The p-type layer except a portion at the gate recess is removed. B ions are implanted in the regrown third electronic barrier layer to reform the ion implanted section. A source electrode and a drain electrode are formed on the third electronic barrier layer. Then a gate electrode is formed on the p-type layer.

The present invention is a FET having a p-doped or acceptor-doped layer underneath a FET channel to enable E/D Mode operation. A FET threshold voltage is tunable through a voltage applied to the p-doped layer via a metal contact such as a threshold-control terminal (TCT). The present invention has a dual E/D mode operation of a single FET device, and also a dual E/D mode operation with a single-polarity positive power supply voltage. The FET of the present invention is fabricated to enable dual enhancement-mode/depletion-mode (E-Mode/D-Mode) high electron mobility transistors (HEMTs), to enable dual E/D Mode operation by incorporating a p-doped or acceptor doped region underneath the channel, to achieve a tunable threshold voltage by varying the bias voltage on a fourth terminal called the threshold-control terminal (TCT) that contacts the p-doped layer, and to enable Dual E/D-Mode operation of a HEMT with a single-polarity positive power supply voltage.

A monolithically integrated device includes a substrate, a first set of Group III nitride epitaxial layers grown for a first HFET on a first region of the substrate, and a second set of Group III nitride epitaxial layers for a second HFET grown on a second region of the substrate.

A method of forming a compound semiconductor substrate includes providing a crystalline base substrate having a first semiconductor material and a main surface, and forming a first semiconductor layer on the main surface and having a pair of tracks disposed on either side of active device regions. The first semiconductor layer is formed from a second semiconductor material having a different coefficient of thermal expansion than the first semiconductor material. The pair of tracks have a relatively weaker crystalline structure than the active device regions. The method further includes thermally cycling the base substrate and the first semiconductor layer such that the first semiconductor layer expands and contracts at a different rate than the base substrate. The pair of tracks physically decouple adjacent ones of the active device regions during the thermal cycling.

A method for manufacturing a HEMT transistor comprising the steps of: providing a wafer comprising a semiconductor body including a heterojunction structure formed by semiconductor materials that include elements of Groups III-V of the Periodic Table, and a dielectric layer on the semiconductor body; etching selective portions of the wafer, thus exposing a portion of the heterojunction structure; forming an interface layer by a surface reconstruction process, of a semiconductor compound formed by elements of Groups III-V of the Periodic Table, in the exposed portion of the heterojunction structure; and forming a gate electrode, including a gate dielectric and a gate conductive region, on said interface layer.