Methods and semiconductor devices are provided. A vertical junction field effect transistor (JFET) includes a substrate, an active region having a plurality of semiconductor fins, a source metal layer on an upper surface of the fins, a source metal pad layer coupled to the semiconductor fins through the source metal layer, a gate region surrounding the semiconductor fins, and a body diode surrounding the gate region.

A lateral super junction JFET is formed from stacked alternating P type and N type semiconductor layers over a P-epi layer supported on an N+ substrate. An N+ drain column extends down through the super junction structure and the P-epi to connect to the N+ substrate to make the device a bottom drain device. N+ source column and P+ gate column extend through the super junction but stop at the P-epi layer. A gate-drain avalanche clamp diode is formed from the bottom the P+ gate column through the P-epi to the N+ drain substrate.

A method for manufacturing a vertical JFET includes providing a III-nitride substrate having a first conductivity type; forming a first III-nitride layer coupled to the III-nitride substrate, wherein the first III-nitride layer is characterized by a first dopant concentration and the first conductivity type; forming a plurality of trenches within the first III-nitride layer, wherein the plurality of trenches extend to a predetermined depth; epitaxially regrowing a second III-nitride structure in the trenches, wherein the second III-nitride structure is characterized by a second conductivity type; forming a plurality of III-nitride fins, each coupled to the first III-nitride layer, wherein the plurality of III-nitride fins are separated by one of a plurality of recess regions; epitaxially regrowing a III-nitride gate layer in the recess regions, wherein the III-nitride gate layer is coupled to the second III-nitride structure, and wherein the III-nitride gate layer is characterized by the second conductivity type.

A method for manufacturing a vertical JFET includes providing a III-nitride substrate having a first conductivity type and forming a first III-nitride layer coupled to the III-nitride substrate. The first III-nitride layer is characterized by a first dopant concentration and the first conductivity type. The method also includes forming a plurality of trenches within the first III-nitride layer and epitaxially regrowing a second III-nitride structure in the trenches. The second III-nitride structure is characterized by a second conductivity type. The method further includes forming a plurality of III-nitride fins, each coupled to the first III-nitride layer, wherein the plurality of III-nitride fins are separated by one of a plurality of recess regions, and epitaxially regrowing a III-nitride gate layer in the recess regions. The III-nitride gate layer is coupled to the second III-nitride structure and the III-nitride gate layer is characterized by the second conductivity type.

A vertical junction field effect transistor (JFET) includes a substrate, an active region having a plurality of semiconductor fins, a source metal layer on an upper surface of the fins, a source metal pad layer coupled to the semiconductor fins through the source metal layer, a gate region surrounding the semiconductor fins, and a body diode surrounding the gate region.

A III-N-based vertical transistor includes a III-N substrate, a source, a drain, and a channel comprising a III-N crystal material and extending between the source and the drain. The channel includes at least one sidewall surface aligned ±0.3° with respect to an m-plane of the III-N crystal material. The III-N-based vertical transistor also includes a gate electrically coupled to the at least one sidewall surface of the channel.

An embodiment relates to a semiconductor component, comprising a semiconductor body of a first conductivity type comprising a voltage blocking layer and islands of a second conductivity type on a contact surface and optionally a metal layer on the voltage blocking layer, and a first conductivity type layer comprising the first conductivity type not in contact with a gate dielectric layer or a source layer that is interspersed between the islands of the second conductivity type.

Fabricating a vertical-channel junction field-effect transistor includes forming an unintentionally doped GaN layer on a bulk GaN layer by metalorganic chemical vapor deposition, forming a Cr/SiO.sub.2 hard mask on the unintentionally doped GaN layer, patterning a fin by electron beam lithography, defining the Cr and SiO.sub.2 hard masks by reactive ion etching, improving a regrowth surface with inductively coupled plasma etching, removing hard mask residuals, regrowing a p-GaN layer, selectively etching the p-GaN layer, forming gate electrodes by electron beam evaporation, and forming source and drain electrodes by electron beam evaporation. The resulting vertical-channel junction field-effect transistor includes a doped GaN layer, an unintentionally doped GaN layer on the doped GaN layer, and a p-GaN regrowth layer on the unintentionally doped GaN layer. Portions of the p-GaN regrowth layer are separated by a vertical channel of the unintentionally doped GaN layer.

A method and vertical FET device fabricated in GaN or other suitable material. The device has a selective area implant region comprising an activated impurity configured from a bottom portion of a recessed regions, and substantially free from ion implant damage by using an annealing process. A gate region is configured from the selective area implant region, and each of the recessed regions is characterized by a depth configured to physically separate an n+ type source region and the p-type gate region such that a low reverse leakage gate-source p-n junction is achieved. An extended drain region is configured from a portion of an n− type GaN region underlying the recessed regions. An n+ GaN region is formed by epitaxial growth directly overlying the backside region of the GaN substrate and a backside drain contact region configured from the n+ type GaN region overlying the backside region.

A field-plate trench FET having a drain region, an epitaxial layer, a source region, a gate conductive layer formed in a trench, a field-plate dielectric layer formed on vertical sidewalls of the trench, a well region formed below the trench, a source contact and a gate contact. When the well region is in direct physical contact with the gate conductive layer, the field-plate trench FET can be used as a normally-on device working depletion mode, and when the well region is electrically isolated from the gate conductive layer by the field-plate layer, the field-plate trench FET can be used as a normally-off device working in an accumulation-depletion mode.