Disclosed is an epitaxial substrate with a 2D material interposer on a surface of a polycrystalline substrate. The ultra-thin 2D material interposer is grown by van der Waals epitaxy. The lattice constant of a surface layer of the ultra-thin 2D material interposer and the coefficient of thermal expansion of the substrate base are highly fit with those of AlGaN or GaN. The ultra-thin 2D material interposer is of a single-layer structure or a composite-layer structure. An AlGaN or GaN single crystalline epitaxial layer is grown on the ultra-thin 2D material interposer by virtue of the van der Waals epitaxy. Therefore, the large-size substrate may be manufactured with far lower costs than related single crystal wafers.

A semiconductor structure comprises a layer of a first III-nitride material having a first lattice dimension; a non-porous layer of a second III-nitride material having a second lattice dimension different from the first lattice dimension; and a porous region of III-nitride material disposed between the layer of first III-nitride material and the non-porous layer of the second III-nitride material. An optoelectronic semiconductor device, an LED, and a method of manufacturing a semiconductor structure are also provided.

According to one embodiment, a nitride semiconductor includes a base body, a nitride member, and an intermediate region provided between the base body and the nitride member. The nitride member includes a first nitride region including Al.sub.x1Ga.sub.1-x1N (0<x1≤1), and a second nitride region including Al.sub.x2Ga.sub.1-x2N (0≤x2<1, x2<x1). The first nitride region is between the intermediate region and the second nitride region. The intermediate region includes nitrogen and carbon. A concentration of carbon in the intermediate region is not less than 1.5×10.sup.19/cm.sup.3 and not more than 6×10.sup.20/cm.sup.3.

Gallium nitride (GaN) integrated circuit technology is described. In an example, an integrated circuit structure includes a substrate including silicon, the substrate having a top surface. A first trench is in the substrate, the first trench having a first width. A second trench is in the substrate, the second trench having a second width less than the first width. A first island is in the first trench, the first island including gallium and nitrogen and having first corner facets below the top surface of the substrate. A second island is in the second trench, the second island including gallium and nitrogen and having second corner facets below the top surface of the substrate.

According to one embodiment, a nitride semiconductor includes a base body, and a nitride member. The nitride member includes a first nitride region including Al.sub.x1Ga.sub.1-x1N (0<x1≤1), and a second nitride region including Al.sub.x2Ga.sub.1-x2N (0≤x2<1, x2<x1). The first nitride region is between the base body and the second nitride region. The first nitride region includes a first portion and a second portion. The second portion is between the first portion and the second nitride region. An oxygen concentration in the first portion is higher than an oxygen concentration in the second portion. The oxygen concentration in the second portion is not more than 1×10.sup.18/cm.sup.3. A first thickness of the first portion in a first direction from the first to second nitride regions is thinner than a second thickness of the second portion in the first direction.

A method for etching at least one layer of a gallium nitride (GaN)-based material is provided, the method including: providing the GaN-based layer having a front face; and at least one cycle including the following successive steps: modifying, by implanting hydrogen (H)- and/or helium (He)-based ions, at least some of a thickness of the GaN-based layer to form in the layer at least one modified portion extending from the front face, the implanting being carried out from a plasma, the modifying by implanting being carried out such that the modified portion extends from the front face and over a depth greater than 3 nm; oxidizing at least some of the modified portion by exposing the layer to an oxygen-based plasma, to define in the layer, at least one oxidized portion and at least one non-oxidized portion; and etching the oxidized portion selectively at the non-oxidized portion.

According to one embodiment, a semiconductor device includes a substrate, and a first semiconductor layer including magnesium and Al.sub.x1Ga.sub.1-x1N. The first semiconductor layer includes first, second, and third regions. The first region is between the substrate and the third region. The second region is between the first and third regions. A first concentration of magnesium in the first region is greater than a third concentration of magnesium in the third region. A second concentration of magnesium in the second region decreases along a first orientation. The first orientation is from the substrate toward the first semiconductor layer. A second change rate of a logarithm of the second concentration with respect to a change of a position along the first orientation is greater than a third change rate of a logarithm of the third concentration with respect to the change of the position along the first orientation.

A method of manufacture and structure for a monolithic single chip single crystal device. The method can include forming a first single crystal epitaxial layer overlying the substrate and forming one or more second single crystal epitaxial layers overlying the first single crystal epitaxial layer. The first single crystal epitaxial layer and the one or more second single crystal epitaxial layers can be processed to form one or more active or passive device components. Through this process, the resulting device includes a monolithic epitaxial stack integrating multiple circuit functions.

A semiconductor thin film structure may include a substrate, a buffer layer on the substrate, and a semiconductor layer on the buffer layer, such that the buffer layer is between the semiconductor layer and the substrate. The buffer layer may include a plurality of unit layers. Each unit layer of the plurality of unit layers may include a first layer having first bandgap energy and a first thickness, a second layer having second bandgap energy and a second thickness, and a third layer having third bandgap energy and a third thickness. One layer having a lowest bandgap energy of the first, second, and third layers of the unit layer may be between another two layers of the first, second, and third layers of the unit layer.

Disclosed is a preparation method for a semiconductor structure. The semiconductor structure includes: a substrate; an epitaxial layer and an epitaxial structure that are stacked on the substrate in sequence. The epitaxial layer is doped with a doping element. In the forming process, a sacrificial layer is formed on the epitaxial layer, and the sacrificial layer is repeatedly etched, such that a concentration of the doping element in the epitaxial layer is lower than a preset value. In this application, the sacrificial layer is formed on the epitaxial layer, and the sacrificial layer is repeatedly etched, such that the concentration of the doping element in the epitaxial layer is lower than the preset value, so as to prevent the doping element in the epitaxial layer from being precipitated upward into an upper-layer structure, ensure the mobility of electrons in a channel layer, and improve the performance of a device.