The present invention discloses a method for preparing large-area transition metal dichalcogenide (TMDC) single-crystal films and the products obtained therefrom. The method comprises the steps of: (1) providing a single-crystal C-plane sapphire with surface steps along <1010> directions; and (2) taking the sapphire in step (1) as the substrate, generating unidirectionally arranged TMDC domains on the sapphire surface based on a vapor deposition method and keeping the domains continuously grow and merge into a large-area single-crystal film. The lateral size of the TMDC single-crystal films prepared by the method can reach inch level or above, and is limited only by the size of the substrate.

A sputtering target for a gallium nitride thin film, which has a low oxygen content, a high density and a low resistivity. A gallium nitride powder having powder physical properties of a low oxygen content and a high bulk density is used and hot pressing is conducted at high temperature in high vacuum to prepare a gallium nitride sintered body having a low oxygen content, a high density and a low resistivity.

Methods for making metastable lead-free piezoelectric materials are presented herein.

Disclosed is a method for manufacturing a piezoelectric Al.sub.xGa.sub.1-xN (0.5≤x≤1) thin film, comprising: forming a stress control layer comprised of a Group III nitride on a silicon substrate by chemical vapor deposition (CVD); and depositing a piezoelectric Al.sub.xGa.sub.1-xN (0.5≤x≤1) thin film on the stress control layer, the thin film being deposited by PVD at 0.3 Tm (Tm is melting temperature of a piezoelectric thin film material) or higher. Further, a method for manufacturing a device in conjunction with piezoelectric Al.sub.xGa.sub.1-xN (0.5≤x≤1) thin films is provided.

A method of forming a semiconductor structure includes forming a first material over a base material by vapor phase epitaxy. The first material has a crystalline portion and an amorphous portion. The amorphous portion of the first material is removed by abrasive planarization. At least a second material is formed by vapor phase epitaxy over the crystalline portion of first material. The second material has a crystalline portion and an amorphous portion. The amorphous portion of the second material is removed by abrasive planarization. A semiconductor structure formed by such a method includes the substrate, the first material, the second material, and optionally, an oxide material between the first material and the second material. The substrate, the first material, and the second material define a continuous crystalline structure. Semiconductor structures, memory devices, and systems are also disclosed.

A method of manufacturing an electronic device is provided. The method includes forming a dielectric layer on a Si-based substrate, etching away portions of the dielectric layer to form a crisscrossing grid pattern of remaining portions of the dielectric layer and to expose the substrate in areas where the dielectric layer is removed, forming GaN-based layers on the substrate in growth areas between sidewalls of the remaining portions of the dielectric layer, and forming a semiconductor device on the GaN-based layers.

Systems and methods for the rapid growth of Group III metal nitrides using plasma assisted molecular beam epitaxy. The disclosure includes higher pressure and flow rates of nitrogen in the plasma, and the application of mixtures of nitrogen and an inert gas. Growth rates exceeding 8 μm/hour can be achieved.

An object is to provide a nonpolar or semipolar GaN substrate having improved size and crystal quality. A self-standing GaN substrate has an angle between the normal of the principal surface and an m-axis of 0 degrees or more and 20 degrees or less, wherein: the size of the projected image in a c-axis direction when the principal surface is vertically projected on an M-plane is 10 mm or more; and when an a-axis length is measured on an intersection line between the principal surface and an A-plane, a low distortion section with a section length of 6 mm or more and with an a-axis length variation within the section of 10.0×10.sup.−5 Å or less is observed.

It is provided a method of growing a group 13 nitride crystal layer, on an underlying substrate including a seed crystal layer composed of a group 13 nitride. The underlying substrate is immersed in a melt containing a flux to grow a group 13 nitride crystal layer two-dimensionally on a nitrogen polar surface of the seed crystal layer by flux method.

The present invention provides a method for manufacturing an epitaxial film and the epitaxial film thereof. The method comprises the steps of: providing a first single crystal substrate and forming a sacrificial layer and a first epitaxial film on the first single crystal substrate; removing the sacrificial layer in order to separate the first epitaxial film from the first single crystal substrate; shifting the first epitaxial film to a second single crystal substrate so as to let the first epitaxial film cover on a partial surface of the second single crystal substrate, wherein the first epitaxial film and the second single crystal substrate are two different crystallographic plane orientations in absolute coordinates; and forming a second epitaxial film on the first epitaxial film and the second single crystal substrate, so as to let the second epitaxial film has at least two crystallographic plane orientations.