A method of processing a silicon surface includes using a first radical species to remove contamination from the surface and to roughen the surface; and using a second radical species to smooth the roughened surface. Reaction systems for performing such a method, and silicon surfaces prepared using such a method, also are provided.

A silicon wafer is provided in which a dopant is phosphorus, resistivity is from 0.5 m.Math.cm to 1.2 m.Math.cm, and carbon concentration is 3.010.sup.16 atoms/cm.sup.3 or more. The carbon concentration is decreased by 10% or more near a surface of the silicon wafer compared with a center-depth of the silicon wafer.

A silicon carbide wafer, including: a semiconductor substrate containing silicon carbide and having a first surface and a second surface opposite to each other; an epitaxial layer provided at the first surface of the semiconductor substrate and having a dopant concentration lower than that a dopant concentration of the semiconductor substrate; and a crystal defect introduced region provided in the semiconductor substrate, at a predetermined depth from the first surface of the semiconductor substrate, the crystal defect introduced region being in contact with the epitaxial layer and containing a number of point defects that are atomic vacancies created by irradiation of an electron beam on the semiconductor substrate.

A method for preparing a super junction trench MOSFET, comprising: providing a substrate, and forming a first trench in the substrate; depositing an epitaxial portion of a first stage in the first trench while supplying a doped gas and an etching gas, and performing an epitaxial process after stopping supplying the doped gas and the etching gas, wherein impurities in the epitaxial portion of the first stage are diffused to an upper portion of the first trench and to form an epitaxial portion of a second stage with a gradient concentration by utilizing a high-temperature environment of the epitaxial process; forming a well region, a trench gate, and an active region in the substrate at a periphery of the first trench; forming an interlayer dielectric layer covering the column, the trench gate, and the active region; and electrically leading out the column, the trench gate, and the active region.

A composite substrate includes: a base substrate and an -Ga.sub.2O.sub.3 crystal film that is provided on the base substrate, has a thickness of 10 m or more, and has at least one alkali metal element content of 1.210.sup.15 atoms/cm.sup.3 or more and 1.010.sup.18 atoms/cm.sup.3 or less.

A gallium nitride substrate has a main surface inclined by 0 to 20 from a (0001) plane and having an area of 15 cm.sup.2 or more. The main surface has a dislocation density of 510.sup.6 cm.sup.2 or less, and a number density of local strains in a crossed Nicols image obtained by a sensitive color method for the main surface is 0.5 cm.sup.2 or less.

Provided are a crack-free laminated film and a structure including this laminated film. This laminated film includes: a buffer layer; and at least one layer of gallium nitride base film disposed on the buffer layer. Moreover, the compression stress of the entire laminated film is 2.0 to 5.0 GPa.

A method for growing a III-V material may include forming at least one layer on a stack including a crystalline layer made of III-V material, a first masking layer surmounting the germination layer, the first masking layer having at least one first opening; depositing a second masking layer covering an upper face of the sacrificial layer; forming at least one second opening in the second masking layer; removing the sacrificial layer selectively at the first masking layer and at the second masking layer; epitaxially growing a material made of the III-V material from the germination layer; forming al least one third opening in the second masking layer; and epitaxially growing at least one material made of the III-V material from the first epitaxial layer.

A laser processing apparatus and a laser processing method that can effectively prevent a processing time for one semiconductor film from increasing are provided. A laser processing apparatus (1) according to an embodiment includes a laser light source (2) configured to irradiate a semiconductor film (M1) with a laser beam, a film state measuring instrument (5) configured to measure a state of the semiconductor film after the semiconductor film (M1) is irradiated with the laser beam, and a laser light adjusting mechanism configured to adjust a timing at which the semiconductor film (M1) is irradiated with a next laser beam and intensity of the laser beam according to the state of the semiconductor film (M1) measured by the film state measuring instrument (5).

The present disclosure provides a method for preparing a gallium nitride (GaN) single-crystal substrate with an edge metal mask technology. The method includes: preparing a metal mask ring on a composite epitaxial substrate, epitaxially growing a GaN single-crystal sacrificial layer in a confined manner, performing separation with interlayer decoupling of single-crystal graphene through an in-situ temperature gradient method to obtain a self-supporting GaN single-crystal sacrificial layer, epitaxially growing a GaN single-crystal thick film in a diameter expanded manner, and performing chemico-mechanical trimming on the GaN single-crystal thick film to obtain a stress-free self-supporting GaN single-crystal substrate. The metal mask ring is compatible with the GaN single-crystal preparation process (hydride vapor phase epitaxy (HVPE)), and efficiently catalyzes decomposition reaction of the nitrogen source. While prohibiting edge growth of the GaN single-crystal thick film, the present disclosure improves a crystalline quality of the GaN single-crystal substrate.