A semiconductor device, includes an insulating film formed on a substrate; a conductive layer, comprising first and second doped poly-silicon regions and a undoped poly-Si region, formed on the insulating film; a highly doped first conductivity type drain region and a highly doped a first conductivity type source region formed in the first and second doped poly-silicon regions, respectively; and a highly doped second conductivity type gate region formed in the undoped poly-Si region between the highly doped first conductivity type drain region and the highly doped first conductivity type source region. The undoped poly-Si region is disposed closer to the highly doped first conductivity type source region than the highly doped first conductivity type drain region.

In an example, an integrated circuit includes a junction-gate field effect transistor (JFET), a current generator, a dynamic filter, and an output transistor. The JFET has a JFET gate, a JFET source, and a JFET drain, the JFET drain adapted to be coupled to a power supply. The current generator has a current generator input and current generator outputs, the current generator input coupled to the JFET source and a first of the current generator outputs coupled to the JFET gate. The dynamic filter has a dynamic filter input and a dynamic filter output, the dynamic filter input coupled to a second of the current generator outputs. The output transistor has an output transistor gate coupled to the dynamic filter output.

A semiconductor device contains a JFET with a channel layer having a first conductivity type in a substrate. The JFET has a back gate having a second, opposite, conductivity type below the channel. The back gate is laterally aligned with the channel layer. The semiconductor device is formed by forming a channel mask over the substrate of the semiconductor device which exposes an area for the channel dopants. The channel dopants are implanted into the substrate in the area exposed by the channel mask while the channel mask is in place. The back gate dopants are implanted into the substrate while the channel mask is in place, so that the implanted channel dopants are laterally aligned with the implanted channel dopants.

A semiconductor device includes: a channel layer which is made of In.sub.pAl.sub.qGa.sub.1-p-qN (0≦p+q≦1, 0≦p, and 0≦q); a barrier layer which is formed on the channel layer and is made of In.sub.rAl.sub.sGa.sub.1-r-sN (0≦r+s≦1, 0≦r) having a bandgap larger than that of the channel layer; a diffusion suppression layer which is selectively formed on the barrier layer and is made of In.sub.tAl.sub.uGa.sub.1-t-uN (0≦t+u≦1, 0≦t, and s>u); a p-type conductive layer which is formed on the diffusion suppression layer and is made of In.sub.xAl.sub.yGa.sub.1-x-yN (0≦x+y≦1, 0≦x, and 0≦y) having p-type conductivity; and a gate electrode which is formed on the p-type conductive layer.

In accordance with the present techniques, there is provided a JFET device structures and methods for fabricating the same. Specifically, there is provided a transistor including a semiconductor substrate having a source and a drain. The transistor also includes a doped channel formed in the semiconductor substrate between the source and the drain, the channel configured to pass current between the source and the drain. Additionally, the transistor has a gate comprising a semiconductor material formed over the channel and dielectric spacers on each side of the gate. The source and the drain are spatially separated from the gate so that the gate is not over the drain and source.

Integrated circuits and methods of producing the same are provided herein. In accordance with an exemplary embodiment, an integrated circuit includes an SOI substrate with an active layer overlying a buried insulator layer that in turn overlies a handle layer. A source is defined within the active layer, and a gate well is also defined within the active layer. A first ultra shallow trench isolation extends into the active layer, where a first portion of the active layer is positioned between the first ultra shallow trench isolation and the buried insulator layer. The first ultra shallow trench isolation is positioned between the source and the gate well.

A transistor (100), including a planar semiconducting substrate (36), a source (42) formed on the substrate, a first drain (102) formed on the substrate, and a second drain (104) formed on the substrate in a location physically separated from the first drain. At least one gate (38, 40) is formed on the substrate and is configured to selectably apply an electrical potential to the substrate in either a first spatial pattern, which causes a first conductive path (62) to be established within the substrate from the source to the first drain, or a second spatial pattern, which causes a second conductive path to be established within the substrate from the source to the second drain.

In an example, an integrated circuit includes a junction-gate field effect transistor (JFET), a current generator, a dynamic filter, and an output transistor. The JFET has a JFET gate, a JFET source, and a JFET drain, the JFET drain adapted to be coupled to a power supply. The current generator has a current generator input and current generator outputs, the current generator input coupled to the JFET source and a first of the current generator outputs coupled to the JFET gate. The dynamic filter has a dynamic filter input and a dynamic filter output, the dynamic filter input coupled to a second of the current generator outputs. The output transistor has an output transistor gate coupled to the dynamic filter output.

A junction field effect transistor (JFET) structure includes a doped polysilicon gate over a channel region of a semiconductor layer. The doped polysilicon gate has a first doping type. A raised epitaxial source is on the source region of the semiconductor layer and adjacent a first sidewall of the doped polysilicon gate, and has a second doping type opposite the first doping type. A raised epitaxial drain is on the drain region of the semiconductor layer and adjacent a second sidewall of the doped polysilicon gate, and has the second doping type. A doped semiconductor region is within the channel region of the semiconductor layer and extending from the source region to the drain region, and a non-conductive portion of the semiconductor layer is within the channel region to separate the doped semiconductor region from the doped polysilicon gate.

A Junction Field Effect Transistor (JFET) has a source and a drain disposed on a substrate. The source and drain have an S/D doping with an S/D doping type. Two or more channels are electrically connected in parallel between the source and drain and can carry a current between the source and drain. Each of the channels has two or more channel surfaces. The channel has the same channel doping type as the S/D doping type. A first gate is in direct contact with one of the channel surfaces. One or more second gates is in direct contact with a respective second channel surface. The gates are doped with a gate doping that has a gate doping type opposite of the channel doping type. A p-n junction (junction gate) is formed where the gates and channel surfaces are in direct contact. The first and second gates are electrically connected so a voltage applied to the first and second gates creates at least two depletion regions in each of the channels. In some embodiments, the junction gates are formed all-around the channel surfaces. As a result, the current flowing in the channels between the source and drain can be controlled with less voltage applied to the gates and less power consumption.