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.

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.

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 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.

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 method for making a device. The method comprises forming a buffer layer on a substrate; forming a periodically doped layer on the buffer layer; forming one or more wires on the periodically doped layer, the wires being chosen from nanowires and microwires; and introducing porosity into the periodically doped layer to form a porous distributed Bragg reflector (DBR). Various devices that can be made by the method are also disclosed.

A method for growth and fabrication of semipolar (Ga,Al,In,B)N thin films, heterostructures, and devices, comprising identifying desired material properties for a particular device application, selecting a semipolar growth orientation based on the desired material properties, selecting a suitable substrate for growth of the selected semipolar growth orientation, growing a planar semipolar (Ga,Al,In,B)N template or nucleation layer on the substrate, and growing the semipolar (Ga,Al,In,B)N thin films, heterostructures or devices on the planar semipolar (Ga,Al,In,B)N template or nucleation layer. The method results in a large area of the semipolar (Ga,Al,In,B)N thin films, heterostructures, and devices being parallel to the substrate surface.