Abstract: An epitaxial structure includes a substrate, a nucleation layer on the substrate, a buffer layer on the nucleation layer, and a nitride layer on the buffer layer. The nucleation layer consists of regions in a thickness direction, wherein a chemical composition of the regions is Al(1-x)InxN, where 0?x?1. A maximum value of the x value in the plurality of regions is the same, a minimum value of the x value in the plurality of regions is the same, and an absolute value of a gradient slope of each of the regions is 0.1%/nm to 50%/nm. A thickness of the nucleation layer is less than a thickness of the buffer layer. A roughness of a surface of the nucleation layer in contact with the buffer layer is greater than a roughness of a surface of the buffer layer in contact with the nitride layer.

Abstract: An epitaxial structure includes a substrate, a buffer layer, a back diffusion barrier layer, a channel layer formed on the back diffusion barrier layer, and a barrier layer formed on the channel layer. The buffer layer is formed on the substrate. The back diffusion barrier layer is formed on the buffer layer. The chemical composition of the back diffusion barrier layer is AlxInyGa1-x-yN, wherein 0?x?1 and 0?y?1. The lattice constant of the back diffusion barrier layer is between 2.9 ? and 3.5 ?. The back diffusion barrier layer is composed of a plurality of regions in the thickness direction, and the aluminum (Al) content and the indium (In) content of the back diffusion barrier layer are changed stepwise or gradually changed stepwise along the thickness direction. The back diffusion barrier layer further includes carbon, and the carbon concentration is changed stepwise or gradually changed stepwise along the thickness direction.

Abstract: An epitaxial structure includes a substrate, a nucleation layer, a buffer layer, and a nitride layer. The nucleation layer is disposed on the substrate, and the nucleation layer consists of a plurality of regions in a thickness direction, wherein a chemical composition of the region is Al(1?x)InxN, where 0?x?1. The buffer layer is disposed on the nucleation layer, and a thickness of the nucleation layer is less than a thickness of the buffer layer. The nitride layer is disposed on the buffer layer, wherein a roughness of a surface of the nucleation layer in contact with the buffer layer is greater than a roughness of a surface of the buffer layer in contact with the nitride layer.

Abstract: An epitaxial structure includes a substrate, a lower super-lattice laminate, a middle super-lattice laminate, an upper super-lattice laminate and a channel layer. The lower super-lattice laminate includes a plurality of first lower film layers and a plurality of second lower film layers stacked alternately. The first lower film layer includes aluminum nitride. The second lower film layer includes aluminum gallium nitride. The middle super-lattice laminate includes a plurality of first middle film layers and a plurality of second middle film layers stacked alternately. The first middle film layer includes aluminum nitride. The second middle film layer includes gallium nitride doped with a doping material. The upper super-lattice laminate includes a plurality of first upper film layers and a plurality of second upper film layers stacked alternately. The first upper film layer includes gallium nitride doped with the doping material. The second upper film layer includes gallium nitride.

Abstract: An epitaxial structure includes a substrate, a buffer layer, a channel layer, a barrier layer, a diffusion barrier layer, and a P-type gallium nitride layer sequentially stacked from bottom to top. The P-type gallium nitride layer has a first lattice constant. The diffusion barrier layer includes a chemical composition of Inx1Aly1Gaz1N, where x1+y1+z1=1, 0?x1?0.3, 0?y1?1.0, and 0?z1?1.0. The chemical composition of the diffusion barrier layer has a proportional relationship so that the diffusion barrier layer has a second lattice constant that matches the first lattice constant, and the second lattice constant is between 80% and 120% of the first lattice constant.

Abstract: An epitaxial structure including at least a substrate, a nucleation layer, a buffer layer, a channel layer, a barrier layer, and a P-type aluminum indium gallium nitride layer is provided. The nucleation layer is formed on the substrate; the buffer layer is formed on the nucleation layer; the channel layer is formed on the buffer layer; the barrier layer is formed on the channel layer; and the P-type aluminum indium gallium nitride layer is formed on the barrier layer. The material of the P-type aluminum indium gallium nitride layer is AlInGaN with a P-type dopant, in which the contents of Al, In and Ga all change stepped-periodically or stepped-periodical-gradually in the thickness direction, and the doping concentration of the P-type dopant changes stepped-periodically or stepped-periodical-gradually in the thickness direction.

Abstract: An epitaxial structure and a semiconductor device are provided in which the epitaxial structure includes at least a SiC substrate, a nucleation layer, and a GaN layer. The nucleation layer is formed on the SiC substrate. The material of the nucleation layer is aluminum gallium nitride doped with a dopant, the Al content in the nucleation layer changes from high to low in the thickness direction, the lattice constant of the nucleation layer is between 3.08 ? and 3.21 ?, and the doping concentration of the nucleation layer changes from high to low in the thickness direction. The GaN layer is formed on the nucleation layer.

Abstract: An epitaxial structure includes a substrate, a buffer layer, a back diffusion barrier layer, a channel layer formed on the back diffusion barrier layer, and a barrier layer formed on the channel layer. The buffer layer is formed on the substrate. The back diffusion barrier layer is formed on the buffer layer. The chemical composition of the back diffusion barrier layer is AlxInyGa1-x-yN, wherein 0?x?1 and 0?y?1. The lattice constant of the back diffusion barrier layer is between 2.9 ? and 3.5 ?. The back diffusion barrier layer is composed of a plurality of regions in the thickness direction, and the aluminum (Al) content and the indium (In) content of the back diffusion barrier layer are changed stepwise or gradually changed stepwise along the thickness direction. The back diffusion barrier layer further includes carbon, and the carbon concentration is changed stepwise or gradually changed stepwise along the thickness direction.

Abstract: An epitaxial structure includes a substrate, a buffer layer, a channel layer, an intermediate layer, and a barrier layer. The buffer layer is disposed on the substrate, the channel layer is disposed on the buffer layer, the barrier layer is disposed on the channel layer, and the intermediate layer is disposed between the channel layer and the barrier layer. The chemical composition of the barrier layer is Alx1Iny1Gaz1N, and the chemical composition of the intermediate layer is Alx2Iny2Gaz2N. The lattice constant of the barrier layer is greater than the lattice constant of the intermediate layer. The aluminum (Al) content of at least a portion of the intermediate layer is greater than the Al content of the barrier layer.

Abstract: An epitaxial structure includes a substrate, a buffer layer, a channel layer, an intermediate layer, and a barrier layer. The buffer layer is disposed on the substrate, the channel layer is disposed on the buffer layer, the barrier layer is disposed on the channel layer, and the intermediate layer is disposed between the channel layer and the barrier layer. The chemical composition of the barrier layer is Alx1Iny1Gaz1N, and the chemical composition of the intermediate layer is Alx2Iny2Gaz2N. The lattice constant of the barrier layer is greater than the lattice constant of the intermediate layer. The aluminum (Al) content of at least a portion of the intermediate layer is greater than the Al content of the barrier layer.

Abstract: An epitaxial structure includes a substrate, a nucleation layer, a buffer layer, and a nitride layer. The nucleation layer is disposed on the substrate, and the nucleation layer consists of a plurality of regions in a thickness direction, wherein a chemical composition of the region is Al(1?x)InxN, where 0?x?1. The buffer layer is disposed on the nucleation layer, and a thickness of the nucleation layer is less than a thickness of the buffer layer. The nitride layer is disposed on the buffer layer, wherein a roughness of a surface of the nucleation layer in contact with the buffer layer is greater than a roughness of a surface of the buffer layer in contact with the nitride layer.

Abstract: A semiconductor device including a substrate, a semiconductor layer, and a buffer structure is provided. The semiconductor layer is located on the substrate. The buffer structure is located between the substrate and the semiconductor layer. The buffer structure includes a plurality of first layers and a plurality of second layers. The first layers and the second layers are alternately stacked with a same pitch or different pitches.

Abstract: A heterostructure, includes: a substrate; and a buffer layer that includes a plurality of layers having a composition AlxInyGa1-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.

Abstract: A heterostructure includes a substrate; an intermediate layer disposed on the substrate; and a group III-V layer having a first primary surface disposed on the intermediate layer and a dopant concentration that varies in a manner including a plurality of ramps with at least one of increasing dopant concentration and decreasing dopant concentration, along the growth direction from the first primary surface throughout the layer's thickness before terminating in a second primary surface.

Abstract: A semiconductor device including a substrate, a semiconductor layer, and a buffer structure is provided. The semiconductor layer is located on the substrate. The buffer structure is located between the substrate and the semiconductor layer. The buffer structure includes a plurality of first layers and a plurality of second layers. The first layers and the second layers are alternately stacked with a same pitch or different pitches.

Abstract: A heterostructure includes a substrate; an intermediate layer disposed on the substrate; and a group III-V layer having a first primary surface disposed on the intermediate layer and a dopant concentration that varies in a manner including a plurality of ramps with at least one of increasing dopant concentration and decreasing dopant concentration, along the growth direction from the first primary surface throughout the layer's thickness before terminating in a second primary surface.