We disclose a III-nitride semiconductor based heterojunction power device comprising: a first heterojunction transistor formed on a substrate, the first heterojunction transistor comprising: a first III-nitride semiconductor region formed over the substrate, wherein the first III-nitride semiconductor region comprises a first heterojunction comprising at least one two dimensional carrier gas; a first terminal operatively connected to the first III-nitride semiconductor region; a second terminal laterally spaced from the first terminal and operatively connected to the first III-nitride semiconductor region; a first plurality of highly doped semiconductor regions of a first polarity formed over the first III-nitride semiconductor region, the first plurality of highly doped semiconductor regions being formed between the first terminal and the second terminal; a first gate region operatively connected to the first plurality of highly doped semiconductor regions; and a second heterojunction transistor formed on the substrate. The second heterojunction transistor comprises: a second III-nitride semiconductor region formed over the substrate, wherein the second III-nitride semiconductor region comprises a second heterojunction comprising at least one two dimensional carrier gas; a third terminal operatively connected to the second III-nitride semiconductor region; a fourth terminal laterally spaced from the third terminal in the first dimension and operatively connected to the second III-nitride semiconductor region; a second gate region being formed over the second III-nitride semiconductor region, and between the third terminal and the fourth terminal. One of the first and second heterojunction transistors is an enhancement mode field effect transistor and the other of the first and second heterojunction transistors is a depletion mode field effect transistor.

Apparatus and circuits including transistors with different threshold voltages and methods of fabricating the same are disclosed. In one example, a semiconductor structure is disclosed. The semiconductor structure includes: a substrate; an active layer that is formed over the substrate and comprises a plurality of active portions; a polarization modulation layer comprising a plurality of polarization modulation portions each of which is disposed on a corresponding one of the plurality of active portions; and a plurality of transistors each of which comprises a source region, a drain region, and a gate structure formed on a corresponding one of the plurality of polarization modulation portions. The transistors have at least three different threshold voltages.

An oxide semiconductor layer which is intrinsic or substantially intrinsic and includes a crystalline region in a surface portion of the oxide semiconductor layer is used for the transistors. An intrinsic or substantially intrinsic semiconductor from which an impurity which is to be an electron donor (donor) is removed from an oxide semiconductor and which has a larger energy gap than a silicon semiconductor is used. Electrical characteristics of the transistors can be controlled by controlling the potential of a pair of conductive films which are provided on opposite sides from each other with respect to the oxide semiconductor layer, each with an insulating film arranged therebetween, so that the position of a channel formed in the oxide semiconductor layer is determined.

In an embodiment, an integrated circuit includes transistors in different active regions, electrically isolated using single diffusion break isolation. The single diffusion break isolation includes a first dummy transistor that has a different threshold voltage than the transistors in either active region for which the single diffusion break is creating isolation. The first dummy transistor may have lower leakage current than transistors in either active region, creating effective isolation between the active regions and consuming relatively small amounts of power due to the lower leakage currents.

Apparatus and circuits with dual polarization transistors and methods of fabricating the same are disclosed. In one example, a semiconductor structure is disclosed. The semiconductor structure includes: a substrate; an active layer that is formed over the substrate and comprises a first active portion having a first thickness and a second active portion having a second thickness; a first transistor comprising a first source region, a first drain region, and a first gate structure formed over the first active portion and between the first source region and the first drain region; and a second transistor comprising a second source region, a second drain region, and a second gate structure formed over the second active portion and between the second source region and the second drain region, wherein the first thickness is different from the second thickness.

A semiconductor device includes a III-V compound semiconductor layer, a III-V compound barrier layer, a gate trench, and a p-type doped III-V compound layer. The III-V compound barrier layer is disposed on the III-V compound semiconductor layer. The gate trench is disposed in the III-V compound barrier layer. The p-type doped III-V compound layer is disposed in the gate trench, and a top surface of the p-type doped III-V compound layer and a top surface of the III-V compound barrier layer are substantially coplanar.

A semiconductor device comprising stacked complimentary transistors are described. In some embodiments, the semiconductor device comprises a first device comprising an enhancement mode III-N heterostructure field effect transistor (HFET), and a second device over the first device. In an example, the second device comprises a depletion mode thin film transistor. In an example, a connector is to couple a first terminal of the first device to a first terminal of the second device.

A method for processing an integrated circuit includes forming first and second gate all around transistors. The method forms a dipole oxide in the first gate all around transistor without forming the dipole oxide in the second gate all around transistor. This is accomplished by entirely removing an interfacial dielectric layer and a dipole-inducing layer from semiconductor nanosheets of the second gate all around transistor before redepositing the interfacial dielectric layer on the semiconductor nanosheets of the second gate all around transistor.

An integrated enhancement/depletion mode high electron mobility transistor (HEMT) includes a substrate, a buffer layer, a first barrier layer, a second barrier layer, a first source, a first drain a first gate, a second source, a second drain, and a second gate. The buffer layer is on the substrate. The first barrier layer is on the buffer layer, and the second barrier layer is on the first barrier layer. The second barrier layer covers a portion of the first barrier layer. The first source, the first drain, and the first gate are on the first barrier layer, and the second source, the second drain, and the second gate are on the second banner layer.

Disclosed herein are IC structures, packages, and devices that include III-N transistor-based cascode arrangements that may simultaneously realize enhancement mode transistor operation and high voltage capability. In one aspect, an IC structure includes a source region, a drain region, an enhancement mode III-N transistor, and a depletion mode III-N transistor, where each of the transistors includes a first and a second source or drain (S/D) terminals. The transistors are arranged in a cascode arrangement in that the first S/D terminal of the enhancement mode III-N transistor is coupled to the source region, the second S/D terminal of the enhancement mode III-N transistor is coupled to the first S/D terminal of the depletion mode III-N transistor, and the second S/D terminal of the depletion mode III-N transistor is coupled to the drain region.