A vertical MOSFET includes a substrate and a first III-nitride layer of a first conductivity type and having a first dopant concentration coupled to the substrate. First trenches are within the first III-nitride layer. A second III-nitride structure of a second dopant concentration and a second conductivity type opposite to the first conductivity type are within the first trenches. A third III-nitride layer of the second conductivity type is coupled to the first III-nitride layer and the second III-nitride structure. A fourth III-nitride layer of the first conductivity type coupled to the third III-nitride layer. Second trenches are within the third and fourth III-nitride layers. A gate dielectric and a gate conductor are within the second trenches. A source conductor is coupled to an upper portion of the fourth III-nitride layer. The first III-nitride layer and the second III-nitride structure provide a charge balance structure.

A semiconductor device includes: a first-conductivity-type semiconductor substrate serving as a drain layer; a first-conductivity-type epitaxial layer formed on the semiconductor substrate; a first-conductivity-type source layer formed in a surface part of the epitaxial layer; two second-conductivity-type gate layers formed in the surface part of the epitaxial layer so as to sandwich the source layer; a first-conductivity-type channel forming layer formed so as to be sandwiched between the two gate layers, the first-conductivity-type channel forming layer being formed on an inner side of the source layer in the epitaxial layer; and an electrode connected to one of the drain layer, the source layer, and the gate layer. In the channel forming layer, two first-conductivity-type impurity layers each having a substantially predetermined width are formed adjacent to each other in a direction crossing a channel.

An electronic device comprising a bidirectional JFET can include a drain/source region; a lightly doped semiconductor layer overlying the drain/source region; a source/drain region overlying the lightly doped semiconductor layer; a trench extending through the source/drain region and into the lightly doped semiconductor layer; a gate electrode of the bidirectional JFET within the trench; and a field electrode within the trench. A process of forming an electronic device can include providing a workpiece including a first doped region and a lightly doped semiconductor layer overlying the first doped region; defining a trench extending into the lightly doped semiconductor layer; forming a gate electrode within the trench, wherein the gate electrode extends to a sidewall of the trench; and forming a field electrode within the trench, wherein a bidirectional JFET includes the first doped region, the lightly doped semiconductor layer, a second doped region, and the gate electrode.

An apparatus includes at least one vertical transistor, where the at least one vertical transistor includes: a substrate including a first semiconductor material, an array of three dimensional (3D) structures above the substrate, a sidewall heterojunction layer positioned on at least one vertical sidewall of each 3D structure, and an isolation region positioned between the 3D structures. Each 3D structure includes the first semiconductor material. The sidewall heterojunction layer includes a second semiconductor material, where the first and second semiconductor material have different bandgaps.