An electronic device can transistor having a channel layer that includes a compound semiconductor material. In an embodiment, the channel layer overlies a semiconductor layer that includes a carrier barrier region and a carrier accumulation region. The charge barrier region can help to reduce the likelihood that de-trapped carriers from the channel layer will enter the charge barrier region, and the charge accumulation region can help to repel carriers in the channel layer away from the charge barrier layer. In another embodiment, a barrier layer overlies the channel layer. Embodiments described herein may help to produce lower dynamic on-resistance, lower leakage current, another beneficial effect, or any combination thereof.

A uni-terminal transistor device is described. In one embodiment, an n-channel transistor comprises a first semiconductor layer having a discrete hole level H.sub.0; a second semiconductor layer having a conduction band minimum E.sub.C2; a wide bandgap semiconductor barrier layer disposed between the first and the second semiconductor layers; a gate dielectric layer disposed above the first semiconductor layer; and a gate metal layer disposed above the gate dielectric layer and having an effective workfunction selected to position the discrete hole level H.sub.0 below the conduction band minimum E.sub.c2 for zero bias applied to the gate metal layer and to obtain n-terminal characteristics.

A multi-layer semiconductor structure is disclosed for use in III-Nitride semiconductor devices, including a channel layer comprising a first III-Nitride material, a barrier layer comprising a second III-Nitride material, a pair of ohmic electrodes disposed in ohmic recesses etched into the barrier layer, a gate electrode disposed in a gate recess etched into the barrier layer, and a filler element. The gate electrode is stepped to form a bottom stem and at least one bottom step within the gate recess. The filler element, comprising an insulating material, is disposed at least below the bottom step of the gate electrode within the gate recess. Also described are methods for fabricating such semiconductor structures. The performance of resulting devices is improved, while providing design flexibility to reduce production cost and circuit footprint.

A process for fabricating a heterojunction field-effect transistor including a semiconductor structure made up of superposed layers, including: providing on a substrate layer (1) a buffer layer (2), a channel layer (3) and a barrier layer (4), the layers being made of materials having hexagonal crystal structures of the Ga.sub.(1-p-q)Al.sub.(p)In.sub.(q)N type; forming an opening in a dielectric masking layer (5) deposited on the barrier layer; growing by high-temperature epitaxy a semiconductor material (6, 6) having a hexagonal crystal structure, namely Ga.sub.(1-x-y)Al.sub.(x)In.sub.(y)N, doped with germanium, on a growth zone defined by the opening formed in the masking layer; and depositing a source or drain contact electrode (15, 16) on the material thus deposited by epitaxy, and a gate electrode (13) in a location outside of the growth zone.

A High Electron Mobility Transistor (HEMT) includes a first III-V compound layer having a first band gap, and a second III-V compound layer having a second band gap over the first III-V compound layer. The second band gap is smaller than the first band gap. The HEMT further includes a third III-V compound layer having a third band gap over the second III-V compound layer, wherein the third band gap is greater than the first band gap. A gate electrode is formed over the third III-V compound layer. A source region and a drain region are over the third III-V compound layer and on opposite sides of the gate electrode.

A multi-layer semiconductor structure is disclosed for use in III-Nitride semiconductor devices, including a channel layer comprising a first III-Nitride material, a barrier layer comprising a second III-Nitride material, a pair of ohmic electrodes disposed in ohmic recesses etched into the barrier layer, a gate electrode disposed in a gate recess etched into the barrier layer, and a filler element. The gate electrode is stepped to form a bottom stem and at least one bottom step within the gate recess. The filler element, comprising an insulating material, is disposed at least below the bottom step of the gate electrode within the gate recess. Also described are methods for fabricating such semiconductor structures. The performance of resulting devices is improved, while providing design flexibility to reduce production cost and circuit footprint.

A heterostructure field effect transistor (HFET) gallium nitride (GaN) semiconductor power device comprises a hetero-junction structure comprises a first semiconductor layer interfacing a second semiconductor layer of two different band gaps thus generating an interface layer as a two-dimensional electron gas (2DEG) layer. The power device further comprises a source electrode and a drain electrode disposed on two opposite sides of a gate electrode disposed on top of the hetero-junction structure for controlling a current flow between the source and drain electrodes in the 2DEG layer. The power device further includes a floating gate located between the gate electrode and hetero-junction structure, wherein the gate electrode is insulated from the floating gate with an insulation layer and wherein the floating gate is disposed above and padded with a thin insulation layer from the hetero-junction structure and wherein the floating gate is charged for continuously applying a voltage to the 2DEG layer to pinch off the current flowing in the 2DEG layer between the source and drain electrodes whereby the HFET semiconductor power device is a normally off device.

Characteristics of a semiconductor device are improved. A semiconductor device includes a potential fixing layer, a channel underlayer, a channel layer, and a barrier layer formed above a substrate, a trench that penetrates the barrier layer and reaches as far as a middle of the channel layer, a gate electrode disposed by way of an insulation film in the trench, and a source electrode and a drain electrode formed respectively over the barrier layer on both sides of the gate electrode. A coupling portion inside the through hole that reaches as far as the potential fixing layer electrically couples the potential fixing layer and the source electrode. This can reduce fluctuation of the characteristics such as a threshold voltage and an on-resistance.

Semiconductor heterostructures having an engineered polarization. Semiconductor materials having specified crystallographic directions and specified polarizations are directly bonded to one another by means of atomic layer bonding without the use of any interfacial bonding materials, where spontaneous polarization of the two layers produced by joining the two materials by direct wafer bonding produces a strong 2DEG or 2DHG at the interface. Embodiments include GaN/AlN and AlN/GaN heterostructures having an N- or Ga-polar GaN layer directly bonded to an N- or Al-polar Al layer. Other embodiments can incorporate an InN epitaxial layer or an alloy incorporating an N-polar, Al-polar, or Ga-polar material having In, Al, or Ga in the crystal lattice, e.g., (In.sub.xAl.sub.1-xN), In.sub.xGa.sub.1-xN, Al.sub.xGa.sub.1-xN, In.sub.xAl.sub.yGa.sub.1-x-yN, where (0<x1, 0<y1, 0<x+y1).

An epitaxial group-ill-nitride buffer-layer structure is provided on a heterosubstrate, wherein the buffer-layer structure has at least one stress-management layer sequence including an interlayer structure arranged between and adjacent to a first and a second group-ill-nitride layer, wherein the interlayer structure comprises a group-ill-nitride interlayer material having a larger band gap than the materials of the first and second group-ill-nitride layers, and wherein a p-type-dopant-concentration profile drops, starting from at least 11018 cm-3, by at least a factor of two in transition from the interlayer structure to the first and second group-ill-nitride layers.