A semiconductor structure includes a buffer layer, a channel layer, a barrier layer, a doped compound semiconductor layer, and a composition gradient layer. The buffer layer is disposed on a substrate, the channel layer is disposed on the buffer layer, the barrier layer is disposed on the channel layer, the doped compound semiconductor layer is disposed on the barrier layer, and the composition gradient layer is disposed between the barrier layer and the doped compound semiconductor layer. The barrier layer and the composition gradient layer include a same group III element and a same group V element, and the atomic percentage of the same group III element in the composition gradient layer is gradually increased in the direction from the barrier layer to the doped compound semiconductor layer. A high electron mobility transistor and a fabrication method thereof are also provided.

A nitride semiconductor laminate includes: a substrate comprising a group III nitride semiconductor and including a surface and a reverse surface, the surface being formed from a nitrogen-polar surface, the reverse surface being formed from a group III element-polar surface and being provided on the reverse side from the surface; a protective layer provided at least on the reverse surface side of the substrate and having higher heat resistance than the reverse surface of the substrate; and a semiconductor layer provided on the surface side of the substrate and comprising a group III nitride semiconductor. The concentration of O in the semiconductor layer is lower than 1×10.sup.17 at/cm.sup.3.

A semiconductor device includes fin patterns on a substrate, at least one gate electrode intersecting the fin patterns, source/drain regions on upper surfaces of the fin patterns, and at least one blocking layer on a sidewall of a first fin pattern of the fin patterns, the at least one blocking layer extending above an upper surface of the first fin pattern of the fin patterns, wherein a first source/drain region of the source/drain regions that is on the upper surface of the first fin pattern has an asymmetric shape and is in direct contact with the at least one blocking layer.

A semiconductor device, including a first semiconductor layer of the first conductivity type formed on a semiconductor substrate, a first semiconductor region of the first conductivity type, a first base region and a first base region, both of a second conductivity type, selectively provided in the first semiconductor layer, a second semiconductor layer of the second conductivity type provided on the first semiconductor layer, a second semiconductor region of the first conductivity type selectively provided in the second semiconductor layer, a trench penetrating the second semiconductor layer and the second semiconductor region, a gate electrode provided in the trench, an interlayer insulating film provided on the gate electrode, a second base region in contact with a bottom of the trench, a first electrode in contact with the second semiconductor layer and the second semiconductor region, and a second electrode provided on the back of the semiconductor substrate.

Methods and systems for selectively depositing material, such as doped semiconductor material, are disclosed. An exemplary method includes providing a substrate, comprising a first area comprising a first material and a second area comprising a second material, selectively depositing a first doped semiconductor layer overlying the first material relative to the second material and selectively depositing a second doped semiconductor layer overlying the first doped semiconductor layer relative to the second material.

A vapor phase epitaxy method of growing a III-V layer with a doping that changes from a first conductivity type to a second conductivity type on a surface of a substrate or a preceding layer in a reaction chamber from the vapor phase from an epitaxial gas flow comprising a carrier gas, at least one first precursor for an element from main group III, and at least one second precursor for an element from main group V, wherein when a first growth height is reached, a first initial doping level of the first conductivity type is set by means of a ratio of a first mass flow of the first precursor to a second mass flow of the second precursor, then the first initial doping level is reduced to a second initial doping level of the first or low second conductivity type.

Methods for activating a p-type dopant in a group III-Nitride semiconductor are provided. In embodiments, such a method comprises annealing, in situ, a film of a group III-Nitride semiconductor comprising a p-type dopant formed via metalorganic chemical vapor deposition (MOCVD) at a first temperature for a first period of time under an atmosphere comprising NH.sub.3 and N.sub.2; and cooling, in situ, the film of the group III-Nitride semiconductor to a second temperature that is lower than the first temperature under an atmosphere comprising N.sub.2 in the absence of NH.sub.3, to form an activated p-type group III-Nitride semiconductor film.

The present disclosure describes epitaxial oxide high electron mobility transistors (HEMTs). In some embodiments, a HEMT comprises: a substrate; a template layer on the substrate; a first epitaxial semiconductor layer on the template layer; and a second epitaxial semiconductor layer on the first epitaxial semiconductor layer. The template layer can comprise crystalline metallic Al(111). The first epitaxial semiconductor layer can comprise (Al.sub.xGa.sub.1-x).sub.yO.sub.z, wherein 0≤x≤1, 1≤y≤3, and 2≤z≤4, wherein the (Al.sub.xGa.sub.1-x).sub.yO.sub.z comprises a Pna21 space group, and wherein the (Al.sub.xGa.sub.1-x).sub.yO.sub.z comprises a first conductivity type formed via polarization. The second epitaxial semiconductor layer can comprise a second oxide material.

The present disclosure provides a semiconductor device structure in accordance with some embodiments. In some embodiments, the semiconductor device structure includes a semiconductor substrate of a first semiconductor material and having first recesses. The semiconductor device structure further includes a first gate stack formed on the semiconductor substrate and being adjacent the first recesses. In some examples, a passivation material layer of a second semiconductor material is formed in the first recesses. In some embodiments, first source and drain (S/D) features of a third semiconductor material are formed in the first recesses and are separated from the semiconductor substrate by the passivation material layer. In some cases, the passivation material layer is free of chlorine.

A buffer layer on a silicon carbide substrate and a method of forming the same are disclosed. The buffer layer includes at least two layers of silicon carbide films, in which at least each lower one is doped at a top surface thereof with predetermined ions. As a result, at the top surface of the silicon carbide film, a barrier with different parameter is formed, which can block dislocation defects that have spread into the silicon carbide film from further upward propagation in the silicon carbide film.