A semiconductor structure (100) comprising: a substrate (102), a first layer (106) of Al.sub.XGa.sub.YIn.sub.(1−X−Y)N disposed on the substrate, stacks (107, 109) of several second and third layers (108, 110) alternating against each other, between the substrate and the first layer, a fourth layer (112) of Al.sub.XGa.sub.YIn.sub.(1−X−Y)N, between the stacks, a relaxation layer of AlN disposed between the fourth layer and one of the stacks, and, in each of the stacks: the level of Ga of the second layers increases from one layer to the next in a direction from the substrate to the first layer, the level of Ga of the third layers is constant or decreasing from one layer to the next in said direction, the average mesh parameter of each group of adjacent second and third layers increasing from one group to the next in said direction, the thickness of the second and third layers is less than 5 nm.

An N-polar III-N high-electron mobility transistor device can include a III-N channel layer over an N-face of a III-N backbarrier, wherein a compositional difference between the channel layer and the backbarrier causes a 2DEG channel to be induced in the III-N channel layer adjacent to the interface between the III-N channel layer and the backbarrier. The device can further include a p-type III-N layer over the III-N channel layer and a thick III-N cap layer over the p-type III-N layer. The III-N cap layer can cause an increase in the charge density of the 2DEG channel directly below the cap layer, and the p-type III-N layer can serve to prevent a parasitic 2DEG from forming in the III-N cap layer.

A high electron mobility transistor (HEMT) includes a substrate, a P-type III-V composition layer, a gate electrode and a carbon containing layer. The P-type III-V composition layer is disposed on the substrate, and the gate electrode is disposed on the P-type III-V composition layer. The carbon containing layer is disposed under the P-type III-V composition layer to function like an out diffusion barrier for preventing from the dopant within the P-type III-V composition layer diffusing into the stacked layers underneath during the annealing process.

A semiconductor device includes a substrate, a semiconductor layer that is provided on the substrate and includes channel layers that are stacked, a source electrode and a drain electrode that are electrically connected to the channel layers, and gate electrodes that are provided between the source electrode and the drain electrode, are arranged in a direction intersecting with a direction from the source electrode to the drain electrode, and are embedded in the semiconductor layer so as to extend from a top face of the semiconductor layer to at least a channel layer closest to the substrate, wherein a width between two adjacent gate electrodes of the gate electrodes in a channel layer farther from the substrate of two channel layers of the channel layers, is narrower than a width between the two adjacent gate electrodes in a channel layer closer to the substrate of the two channel layers.

Embodiments of the present application disclose a semiconductor device and a manufacturing method thereof. The semiconductor device includes a semiconductor layer, a first doped nitride semiconductor layer disposed on the semiconductor layer, and a second doped nitride semiconductor layer disposed on the first doped nitride semiconductor layer. The semiconductor device further includes an undoped nitride semiconductor layer between the semiconductor layer and the first doped nitride semiconductor layer. The undoped nitride semiconductor layer has a first surface in contact with the semiconductor layer and a second surface in contact with the first doped nitride semiconductor layer.

An epitaxial structure for a high-electron-mobility transistor includes a substrate, a nucleation layer, a buffer layered unit, a channel layer, and a barrier layer sequentially stacked on one another in such order. The buffer layered unit includes at least one multiple quantum well structure containing a plurality of p-i-n heterojunction stacks. Each of the p-i-n heterojunction stacks includes p-type, i-type, and n-type layers which are alternately stacked along a direction away from the nucleation layer, and which are made of materials respectively represented by chemical formulas of Al.sub.xGa.sub.(1-x)N, Al.sub.yGa.sub.(1-y)N, and Al.sub.zGa.sub.(1-z)N. For each of the p-i-n heterojunction stacks, x gradually decreases and z gradually increases along the direction away from the nucleation layer, and y is consistent and ranges from 0 to 0.7.

A high electron mobility transistor (HEMT) includes a channel layer, a plurality of barrier layers, and a p-type semiconductor layer. The barrier layers have an energy band gap greater than that of the channel layer. A gate electrode is arranged on the p-type semiconductor layer. A source electrode and a drain electrode are apart from the p-type semiconductor layer and the gate electrode on the barrier layers. Impurity concentrations of the barrier layers are different from each other in a drift area between the source electrode and the drain electrode.

One or more semiconductor structures comprising a hole draining structure are provided. A semiconductor structure has a first layer formed over a substrate. The first layer has a first concentration of a metal material. The semiconductor structure has a second layer formed over the first layer. The second layer has a second concentration of the metal material different than the first concentration of the metal material. The semiconductor structure has a hole draining structure formed from a superlattice formed between the first layer and the second layer. The hole draining structure has a concentration of the metal material increasing towards the first layer and decreasing towards the second layer.

Provided is a compound semiconductor device that can suppress the deterioration of the element characteristics and a method of manufacturing a compound semiconductor device. The compound semiconductor device includes a laminated body constituted of a compound semiconductor and including a channel layer in which a first conductivity type carrier runs; a gate electrode provided on an upper surface side of the laminated body; a source electrode provided on the upper surface side of the laminated body; and a drain electrode provided on the upper surface side of the laminated body. The laminated body includes a second conductivity type first low resistance layer that is provided at a position facing the gate electrode and is in contact with the gate electrode, a first electric-field relaxation layer extended from the first low resistance layer toward a side of one of the source electrode and the drain electrode and configured to relax electric field concentration to the first low resistance layer, and a first amorphous layer covering a first side surface that is a side surface of the first electric-field relaxation layer and faces one of the source electrode and the drain electrode.

A high electron mobility transistor (HEMT) includes a substrate, a P-type III-V composition layer, a gate electrode and a carbon containing layer. The P-type III-V composition layer is disposed on the substrate, and the gate electrode is disposed on the P-type III-V composition layer. The carbon containing layer is disposed under the P-type III-V composition layer to function like an out diffusion barrier for preventing from the dopant within the P-type III-V composition layer diffusing into the stacked layers underneath during the annealing process.