A semiconductor structure includes a substrate, a first nitride layer, a second nitride layer, a third nitride layer, and a polarity inversion layer. The first nitride layer is formed on the substrate, and the polarity inversion layer formed at a surface of the first nitride layer converts a non-metallic polar surface of the first nitride layer into a metallic polar surface of the polarity inversion layer. The second nitride layer is formed on the polarity inversion layer. The third nitride layer is formed on the second nitride layer.

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.

Structures described herein may include mechanically bonded interlayers for formation between a first Group III-V semiconductor layer and a second semiconductor layer. The mechanically bonded interlayers provide reduced lattice strain by strain balancing between the Group III-V semiconductor layer and the second semiconductor layer, which may be silicon.

A silicon carbide crystal includes a seed layer, a bulk layer, and a stress buffering structure formed between the seed layer and the bulk layer. The seed layer, the bulk layer, and the stress buffering structure are each formed with a dopant that cycles between high and low dopant concentration. The stress buffering structure includes a plurality of stacked buffer layers and a transition layer over the buffer layers. The buffer layer closest to the seed layer has the same variation trend of the dopant concentration as the buffer layer closest to the transition layer, and the dopant concentration of the transition layer is equal to the dopant concentration of the seed layer.

A semiconductor device includes a gate structure on a substrate and an epitaxial layer adjacent to the gate structure, in which the epitaxial layer includes a first buffer layer, a second buffer layer on the first buffer layer, a bulk layer on the second buffer layer, a first cap layer on the bulk layer, and a second cap layer on the first cap layer. Preferably, the bottom surface of the first buffer layer includes a linear surface, a bottom surface of the second buffer layer includes a curve, and the second buffer layer includes a linear sidewall.

A heterostructure, includes: a substrate; and a buffer layer that includes a plurality of layers having a composition Al.sub.xIn.sub.yGa.sub.1-x-yN, where x≤1 and y≥0; wherein the buffer layer has a first region that includes at least two layers, a second region that includes at least two layers, and a third region that includes at least two layers.

A high electron mobility transistor includes: a first semiconductor layer over a substrate, and a second semiconductor layer over the first semiconductor layer, the second semiconductor layer having a band gap discontinuity with the first semiconductor layer, and at the first semiconductor layer and/or the second conductive layer includes indium. A top layer is over the second semiconductor layer, and a metal layer is over, and extends into, the top layer, the top layer separating the metal layer from the second semiconductor layer. A gate electrode is over the top layer, a third semiconductor layer being between the gate electrode and the top layer, where a sidewall of the third semiconductor layer and a sidewall of the metal layer are separated. A source and drain are on opposite sides of the gate electrode, the top layer extending continuously from below the source, below the gate electrode, and below the drain.

Disclosed herein are a III-N semiconductor structure manufactured by growing a III-N material on a superlattice structure layer, formed of AlGaN and InAlN materials, which serves as a buffer layer, and a method for manufacturing the same. The disclosed III-N semiconductor structure includes: a substrate including a silicon material; a seed layer formed on the substrate and including an aluminum nitride (AlN) material; a superlattice structure layer formed by sequentially depositing a plurality of superlattice units on the seed layer; and a cap layer formed on the superlattice structure layer and including a gallium nitride (GaN) material, wherein the superlattice units are each composed of a first layer including an AlxGa1-xN wherein 0≤x≤1 and a second layer including an InyAl1-yN wherein 0y≤0.4.

A semiconductor structure includes a substrate. The semiconductor structure further includes a buffer layer over the substrate, wherein the buffer layer comprises a plurality of III-V layers, and a dopant type of each III-V layer of the plurality of III-V layers is opposite to a dopant of adjacent III-V layers of the plurality of III-V layers. The semiconductor structure further includes an active layer over the buffer layer. The semiconductor structure further includes a dielectric layer over the active 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.