Abstract: A method for manufacturing an optical semiconductor device includes the steps of preparing a substrate product including a semiconductor layer, a mesa structure, and a protective layer; forming a buried layer composed of a resin on the substrate product; forming a first opening in the buried layer on the mesa structure; forming a second opening in the buried layer on the semiconductor layer; exposing the mesa structure and the semiconductor layer by etching the protective layer; forming a first electrode in the first opening; and forming a second electrode in the second opening. The step of forming the second opening includes a first etching step including etching the buried layer using a first resist mask for forming a recess and a second etching step including etching the buried layer using a second resist mask having an opening pattern which has an opening width not smaller than that of the recess.

Abstract: A semiconductor substrate includes an AlN layer that is formed so as to contact a Si substrate and has an FWMH of a rocking curve of a (002) plane by x-ray diffraction, the FWMH being less than or equal to 1500 seconds, and a GaN-based semiconductor layer formed on the AlN layer.

Abstract: A method for fabricating a semiconductor device includes forming an AlN layer on a substrate made of silicon by supplying an Al source without supplying a N source and then supplying both the Al source and the N source, and forming a GaN-based semiconductor layer on the AlN layer after the forming of the AlN layer. The forming of the AlN layer grows the AlN layer so as to satisfy the following: 76500/x0.81<y<53800/x0.83 where x is a thickness of the AlN layer and y is an FWHM of a rocking curve of a (002) plane of the AlN layer.

Abstract: An electrostatic chuck device including: a plurality of adsorption areas having an electrode generating electrostatic attractive force; and a control portion controlling the electrostatic attractive force against each of the plurality of the adsorption areas independently of other adsorption areas.

Abstract: A method for fabricating a semiconductor device includes forming an AlN layer on a substrate made of silicon by supplying an Al source without supplying a N source and then supplying both the Al source and the N source, and forming a GaN-based semiconductor layer on the AlN layer after the forming of the AlN layer. The forming of the AlN layer grows the AlN layer so as to satisfy the following: 76500/x0.81y<53800/x0.83 where x is a thickness of the AlN layer and y is an FWHM of a rocking curve of a (002) plane of the AlN layer.

Abstract: A semiconductor substrate inclu8des an AlN layer that is formed so as to contact a Si substrate and has an FWMH of a rocking curve of a (002) plane by x-ray diffraction, the FWMH being less than or equal to 1500 seconds, and a GaN-based semiconductor layer formed on the AlN layer.

Abstract: A semiconductor device includes a Si substrate having a principal plane that is a crystal surface inclined at an off angle of 0.1 degrees or less with respect to a (111) plane, an AlN layer that is provided so as to contact the principal plane of the Si substrate and is configured so that an FWHM of a rocking curve of a (002) plane by x-ray diffraction is not greater than 2000 seconds, and a GaN-based semiconductor layer formed on the AlN layer.

Abstract: A method for fabricating a semiconductor device includes performing thermal cleaning for a surface of a silicon substrate in an atmosphere including hydrogen under a condition that a thermal cleaning temperature is higher than or equal to 700° C. and is lower than or equal to 1060° C., and a thermal cleaning time is longer than or equal to 5 minutes and is shorter than or equal to 15 minutes; forming a first AlN layer on the substrate with a first V/III source ratio, the forming of the first AlN layer including supplying an Al source to the surface of the substrate without supplying a N source, and supplying both the Al source and the N source; forming a second AlN layer on the first AlN layer with a second V/III source ratio that is greater than the first ratio; and forming a GaN-based semiconductor layer on the second AlN layer.