Abstract: A damper device that suppresses arc discharge between electrodes generated by bubbles in an electro-rheological fluid, includes an inner tube housed in an outer tube forming an outer shell of a damper device. An electrode tube is arranged between the outer tube and the inner tube. An electro-rheological fluid is sealed in the outer tube. The inner tube and the electrode tube constitute a cathode and an anode, respectively, and apply a voltage to the electro-rheological fluid located between the inner tube and the electrode tube. An insulating layer is provided on a surface of the electrode tube on a side facing the inner tube or on a surface of the inner tube on a side facing the electrode tube. When a maximum voltage applied to the electro-rheological fluid is Vmax (V), a thickness t (m) of the insulating layer is set to satisfy Formula (1).

Abstract: According to one embodiment, a method for manufacturing a semiconductor device includes placing a substrate having a to-be-processed layer on a stage within an etching chamber and supplying an etching gas into the etching chamber while keeping the stage at a first temperature to perform an etching treatment to etch the to-be-processed layer on the substrate by using a reactive ion etching method. After the etching treatment, and without exposing the substrate to the atmosphere, supplying an inert gas into the etching chamber while keeping the stage at a second temperature, which is higher than the first temperature, to perform a high-temperature treatment to heat the to-be-processed layer.

Abstract: A gallium nitride crystal having a hexagonal crystal structure includes a first region located on an inner side of a cross section intersecting c-axis of the hexagonal crystal structure, and a second region surrounding at least a part of the outer periphery of the first region in the cross section. An emission spectrum of each of the first region and the second region with electron beam or ultraviolet light excitation has a first peak including a band edge emission of gallium nitride and a second peak located in a longer wavelength area than the first peak. A peak intensity of the first peak is smaller than a peak intensity of the second peak in the first region, and a peak intensity of the first peak is greater than a peak intensity of the second peak in the second region.

Abstract: A group 13 nitride crystal having a hexagonal crystal structure and containing at least a nitrogen atom and at least a metal atom selected from a group consisting of B, Al, Ga, In, and Tl. The group 13 nitride crystal includes a first region disposed on an inner side in a cross section intersecting c-axis, a third region disposed on an outermost side in the cross section and having a crystal property different from that of the first region, and a second region disposed at least partially between the first region and the third region in the cross section, the second region being a transition region of a crystal growth and having a crystal property different from that of the first region and that of the third region.

Abstract: A gallium nitride crystal having a hexagonal crystal structure, wherein a full width at half maximum (FWHM) of X-ray rocking curve in a region at a side of one edge in a c-axis direction is smaller than the FWHM in a region at a side of the other edge in the c-axis direction, in at least one of m-plane outer peripheral surfaces of the hexagonal crystal structure.

Abstract: A method of manufacturing a group 13 nitride crystal includes a crystal growth process to form the group 13 nitride crystal by growing the group 13 nitride crystal having a hexagonal crystal structure from a seed crystal which is a gallium nitride crystal having a hexagonal crystal structure in which a length “L” in a c-axis direction is 9.7 mm or more, and a ratio L/d of the length “L” to a crystal diameter “d” in a c-plane is larger than 0.813. The crystal growth process includes a process of forming an outer periphery containing a {10-10} plane and an outer periphery containing a {10-11} plane at side surfaces of the group 13 nitride crystal, and forming an outer periphery containing a {0001} plane at a bottom surface of the group 13 nitride crystal.

Abstract: A gallium nitride crystal having a hexagonal crystal structure includes a first region located on an inner side of a cross section intersecting c-axis of the hexagonal crystal structure, and a second region surrounding at least a part of the outer periphery of the first region in the cross section. An emission spectrum of each of the first region and the second region with electron beam or ultraviolet light excitation has a first peak including a band edge emission of gallium nitride and a second peak located in a longer wavelength area than the first peak. A peak intensity of the first peak is smaller than a peak intensity of the second peak in the first region, and a peak intensity of the first peak is greater than a peak intensity of the second peak in the second region.

Abstract: A group 13 nitride crystal has a hexagonal crystal structure and at least contains nitrogen atom and at least a kind of metal atoms selected from a group consisting of B, Al, Ga, In, and Tl. The group 13 nitride crystal includes a first region located at an inner side of a cross section intersecting a c-axis, and a second region surrounding at least a part of an outer periphery of the first region, having a thickness larger than a maximum diameter of the first region, and having a carrier density higher than that of the first region.

Abstract: A group 13 nitride crystal having a hexagonal crystal structure and containing at least a nitrogen atom and at least a metal atom selected from a group consisting of B, Al, Ga, In, and Tl. The group 13 nitride crystal includes a first region disposed on an inner side in a cross section intersecting c-axis, a third region disposed on an outermost side in the cross section and having a crystal property different from that of the first region, and a second region disposed at least partially between the first region and the third region in the cross section, the second region being a transition region of a crystal growth and having a crystal property different from that of the first region and that of the third region.

Abstract: A gallium nitride crystal having a hexagonal crystal structure, wherein a full width at half maximum (FWHM) of X-ray rocking curve in a region at a side of one edge in a c-axis direction is smaller than the FWHM in a region at a side of the other edge in the c-axis direction, in at least one of m-plane outer peripheral surfaces of the hexagonal crystal structure.

Abstract: A gallium nitride crystal having a hexagonal crystal structure includes a first region located on an inner side of a cross section intersecting c-axis of the hexagonal crystal structure, and a second region surrounding at least a part of the outer periphery of the first region in the cross section. An emission spectrum of each of the first region and the second region with electron beam or ultraviolet light excitation has a first peak including a band edge emission of gallium nitride and a second peak located in a longer wavelength area than the first peak. A peak intensity of the first peak is smaller than a peak intensity of the second peak in the first region, and a peak intensity of the first peak is greater than a peak intensity of the second peak in the second region.

Abstract: A group 13 nitride crystal has a hexagonal crystal structure and at least contains nitrogen atom and at least a kind of metal atoms selected from a group consisting of B, Al, Ga, In, and Tl. The group 13 nitride crystal includes a first region located at an inner side of a cross section intersecting a c-axis, and a second region surrounding at least a part of an outer periphery of the first region, having a thickness larger than a maximum diameter of the first region, and having a carrier density higher than that of the first region.

Abstract: A method of manufacturing a group 13 nitride crystal includes a crystal growth process to form the group 13 nitride crystal by growing the group 13 nitride crystal having a hexagonal crystal structure from a seed crystal which is a gallium nitride crystal having a hexagonal crystal structure in which a length “L” in a c-axis direction is 9.7 mm or more, and a ratio L/d of the length “L” to a crystal diameter “d” in a c-plane is larger than 0.813. The crystal growth process includes a process of forming an outer periphery containing a {10-10} plane and an outer periphery containing a {10-11} plane at side surfaces of the group 13 nitride crystal, and forming an outer periphery containing a {0001} plane at a bottom surface of the group 13 nitride crystal.

Abstract: A large sized bulk crystal is produced which allows to cut out a practical size of crystal substrate. The gallium nitride crystal has features in which a length L of c-axis is 9 mm or more, a crystal diameter d of a cross section orthogonal to the c-axis is 100 ?m, and a ratio L/d of the length L of the c-axis and the crystal diameter d of the cross section orthogonal to the c-axis is 7 or more. By enlarging this elongated needle-like crystal, a bulk crystal with a large volume can be produced, and a large sized bulk crystal can be produced which allows to cut out a practical size of crystal substrate.