Abstract: An ultraviolet semiconductor light emitting device includes a semiconductor stack, a trench, a filling insulator, and first and second electrodes. The semiconductor stack includes first and second conductivity-type semiconductor layers and an active layer therebetween that includes an AlGaN semiconductor material. The trench extends through the second conductivity-type semiconductor layer and the active layer to the first conductivity-type semiconductor layer and has a first width. The filling insulator fills the trench such that the filling insulator extends at least through the active layer in the trench and includes of an insulating material having a particular refractive index. The first electrode is connected to the first conductivity-type semiconductor layer, and the second electrode is connected to the second conductivity-type semiconductor layer.

Abstract: Provided are a hollow drive shaft and a method for manufacturing the same in which a concentrated load to a weak point which may be occurred by differences of sectional thicknesses and outer diameters of the shaft is dispersed so that the strength may be uniform throughout the whole length of the drive shaft. The hollow drive shaft includes: one or more small-diameter portion having a hollow shape; and a large-diameter portion which is disposed in a vicinity of the small-diameter portion and has an outer diameter relatively greater than the small-diameter portion. A sectional thickness of the large-diameter portion is less than a sectional thickness of the small-diameter portion, and a first sectional portion from an outer surface to a point corresponding to 35% to 60% of a sectional thickness of the large-diameter portion is carburized to have a first hardness.

Abstract: The present invention has been made in an effort to provide a hollow drive shaft and a method for manufacturing the same in which the concentrated load to a weak point which may be occurred by differences of sectional thicknesses and outer diameters is dispersed so that the strength may be uniform throughout the whole length. A hollow drive shaft includes: one or more small-diameter portion having a hollow shape; and a large-diameter portion which is disposed in the vicinity of the small-diameter portion and has an outer diameter relatively greater than the small-diameter portion. A sectional thickness of the large-diameter portion is less than a sectional thickness of the small-diameter portion, and a first sectional portion from an outer surface to a point corresponding to 35% to 60% of a sectional thickness of the large-diameter portion is carburized to have a first hardness.

Abstract: An apparatus for evaluating the quality of a crystal includes an optical device that measures a surface reflectance of a wafer in which a V-pit is formed; and a data processing unit that calculates a threading dislocation density by calculating a difference in surface reflectance of the wafer that is measured by the optical device.

Abstract: A method for fabricating a nitride semiconductor thin film includes preparing a first nitride single crystal layer doped with an n-type impurity. A plurality of etch pits are formed in a surface of the first nitride single crystal layer by applying an etching gas thereto. A second nitride single crystal layer is grown on the first nitride single crystal layer having the etch pits formed therein.

Abstract: A method of fabricating a nitride semiconductor light emitting device is provided. The method includes growing a first group-III-nitride semiconductor layer on a substrate, the first group-III-nitride semiconductor layer having a top surface formed as a group-III-rich surface exhibiting a group-III-polarity and a bottom surface formed as a N-rich surface exhibiting a N-polarity. The method further includes selectively etching a N-polarity region in the top surface of the first group III nitride semiconductor layer, forming a second group III nitride semiconductor layer on the first group III nitride semiconductor layer to fill the etched N-polarity region and forming a light emitting structure including first and second conductivity type nitride semiconductor layers and an active layer on the second group III nitride semiconductor layer.

Abstract: An apparatus for evaluating the quality of a crystal includes an optical device that measures a surface reflectance of a wafer in which a V-pit is formed; and a data processing unit that calculates a threading dislocation density by calculating a difference in surface reflectance of the wafer that is measured by the optical device.

Abstract: A method for fabricating a nitride semiconductor thin film includes preparing a first nitride single crystal layer doped with an n-type impurity. A plurality of etch pits are formed in a surface of the first nitride single crystal layer by applying an etching gas thereto. A second nitride single crystal layer is grown on the first nitride single crystal layer having the etch pits formed therein.

Abstract: A method of fabricating a nitride semiconductor light emitting device is provided. The method includes growing a first group-III-nitride semiconductor layer on a substrate, the first group-III-nitride semiconductor layer having a top surface formed as a group-III-rich surface exhibiting a group-III-polarity and a bottom surface formed as a N-rich surface exhibiting a N-polarity. The method further includes selectively etching a N-polarity region in the top surface of the first group III nitride semiconductor layer, forming a second group III nitride semiconductor layer on the first group III nitride semiconductor layer to fill the etched N-polarity region and forming a light emitting structure including first and second conductivity type nitride semiconductor layers and an active layer on the second group III nitride semiconductor layer.

Abstract: There are provided a semiconductor light emitting device and a method of manufacturing the same. The semiconductor light emitting device includes a base layer configured of a group III nitride semiconductor, a polarity modifying layer formed on a group III element polar surface of the base layer, and a light emitting laminate having a multilayer structure of the group III nitride semiconductor formed on the polarity modifying layer, an upper surface of at least one layer in the multilayer structure being formed of an N polar surface.

Abstract: A semiconductor light emitting device includes first and second conductivity-type semiconductor layers formed of AlxGayIn1-x-yP (0?x?1, 0?y?1, 0?x+y?1) or AlzGa1-zAs (0?z?1) and an active layer interposed between the first and second conductivity-type semiconductor layers, wherein at least one of the first and second conductivity-type semiconductor layers includes a low refractive index surface layer formed of (AlvGa1-v)0.5In0.5P (0.7?v?1) or AlwIn1-wP (0?w?1) and having depressions and protrusions.