A nitride epitaxial structure is provided, including: a substrate; a nucleation layer, formed on the substrate, where the nucleation layer is an aluminum nitride layer or a gallium nitride layer; a buffer layer, formed on the nucleation layer, including K stacked group-III nitride double-layer structures, K ≥ 3, each double-layer structure includes an upper layer and a lower layer that are stacked, a band gap difference of each double-layer structure is a difference between a band gap of a material of the upper layer and a band gap of a material of the lower layer, and band gap differences of the K double-layer structures generally present a gradient trend along a thickness direction of the buffer layer; and an epitaxial layer, formed on the buffer layer, where a material of the epitaxial layer includes group-III nitride. A semiconductor device is further provided, including the nitride epitaxial structure.

A nitride epitaxial structure is provided, including: a substrate; a nucleation layer, formed on the substrate, where the nucleation layer is an aluminum nitride layer or a gallium nitride layer; a buffer layer, formed on the nucleation layer, including K stacked group-III nitride double-layer structures, K ≥ 3, each double-layer structure includes an upper layer and a lower layer that are stacked, a band gap difference of each double-layer structure is a difference between a band gap of a material of the upper layer and a band gap of a material of the lower layer, and band gap differences of the K double-layer structures generally present a gradient trend along a thickness direction of the buffer layer; and an epitaxial layer, formed on the buffer layer, where a material of the epitaxial layer includes group-III nitride. A semiconductor device is further provided, including the nitride epitaxial structure.

A film structure (10) includes a substrate (11), a piezoelectric film (14) formed on the substrate (11) and containing first composite oxide represented by a composition formula Pb(Zr.sub.1-xTi.sub.x)O.sub.3, and a piezoelectric film (15) formed on the piezoelectric film (14) and containing second composite oxide represented by a composition formula Pb(Zr.sub.1-yTi.sub.y)O.sub.3. In the composition formulae, x satisfies 0.10<x≤0.20, and y satisfies 0.35≤y≤0.55. The piezoelectric film (14) has tensile stress, and the piezoelectric film (15) has compressive stress.

A film structure (10) includes a substrate (11), a piezoelectric film (14) formed on the substrate (11) and containing first composite oxide represented by a composition formula Pb(Zr.sub.1-xTi.sub.x)O.sub.3, and a piezoelectric film (15) formed on the piezoelectric film (14) and containing second composite oxide represented by a composition formula Pb(Zr.sub.1-yTi.sub.y)O.sub.3. In the composition formulae, x satisfies 0.10<x≤0.20, and y satisfies 0.35≤y≤0.55. The piezoelectric film (14) has tensile stress, and the piezoelectric film (15) has compressive stress.

A vapor phase growth apparatus according to an embodiment includes a reaction chamber; a substrate holder having a holding wall capable holding an outer periphery of the substrate; a process gas supply part provided above the reaction chamber, the process gas supply part having a first region supplying a first process gas and a second region around the first region supplying a second process gas having a carbon/silicon atomic ratio higher than that of the first process gas, an inner peripheral diameter of the second region being 75% or more and 130% or less of a diameter of the holding wall; a sidewall provided between the process gas supply part and the substrate holder, an inner peripheral diameter of the sidewall being 110% or more and 200% or less of an outer peripheral diameter of the second region; a first heater; a second heater; and a rotation driver.

A vapor phase growth apparatus according to an embodiment includes a reaction chamber; a substrate holder having a holding wall capable holding an outer periphery of the substrate; a process gas supply part provided above the reaction chamber, the process gas supply part having a first region supplying a first process gas and a second region around the first region supplying a second process gas having a carbon/silicon atomic ratio higher than that of the first process gas, an inner peripheral diameter of the second region being 75% or more and 130% or less of a diameter of the holding wall; a sidewall provided between the process gas supply part and the substrate holder, an inner peripheral diameter of the sidewall being 110% or more and 200% or less of an outer peripheral diameter of the second region; a first heater; a second heater; and a rotation driver.

Superlattices and methods of making them are disclosed herein. The superlattices are prepared by irradiating a sample to prepare an alternating superlattice of layers of a first material and a second material, wherein the ratio of the first deposition rate to the second deposition rate is between 1.0:2.0 and 2.0:1.0. The superlattice comprises a multiplicity of alternating layers, wherein the multiplicity of layers of the first material have a thickness between 0.1 nm and 50.0 nm or the multiplicity of layers of the second material have a thickness between 0.1 nm and 50.0.

Provided are an atomic layer sheet that contains boron and oxygen as framework elements, is networked by nonequilibrium couplings having boron-boron bonds, and has a molar ratio of oxygen to boron (oxygen/boron) of less than 1.5, a laminated sheet containing a plurality of such atomic layer sheets and metal ions between ones of the sheets, and a thermotropic liquid crystal and a lyotropic liquid crystal containing these. In addition, there is provided a method for manufacturing an atomic layer sheet and/or a laminated sheet containing boron and oxygen, the method including: adding MBH.sub.4, where M represents an alkali metal ion, into a solvent containing an organic solvent in an inert gas atmosphere to prepare a solution; and exposing the solution to an atmosphere containing oxygen.

Provided are an atomic layer sheet that contains boron and oxygen as framework elements, is networked by nonequilibrium couplings having boron-boron bonds, and has a molar ratio of oxygen to boron (oxygen/boron) of less than 1.5, a laminated sheet containing a plurality of such atomic layer sheets and metal ions between ones of the sheets, and a thermotropic liquid crystal and a lyotropic liquid crystal containing these. In addition, there is provided a method for manufacturing an atomic layer sheet and/or a laminated sheet containing boron and oxygen, the method including: adding MBH.sub.4, where M represents an alkali metal ion, into a solvent containing an organic solvent in an inert gas atmosphere to prepare a solution; and exposing the solution to an atmosphere containing oxygen.

Methods and systems for forming structures including a superlattice of silicon-containing epitaxial layers using nanoparticles. Exemplary methods can include forming nanoparticles in situ and depositing the nanoparticles onto a substrate surface to thereby form the epitaxial layers.