Abstract: There is provided a semiconductor device, including: a semiconductor member having a mesa structure in which a second semiconductor layer having one of a p-type conductivity type and an n-type conductivity type is laminated on a first semiconductor layer having the other one of the p-type conductivity type and the n-type conductivity type, so that the second semiconductor layer is exposed on an upper surface of the mesa structure, a pn junction interface is exposed on a side surface of the mesa structure, and the first semiconductor layer is exposed on an outside upper surface of the mesa structure; an insulating film disposed on a side surface of the mesa structure and on an outside upper surface of the mesa structure; a first electrode electrically connected to the second semiconductor layer on the upper surface of the mesa structure, and extends on the side surface of the mesa structure and on the outside upper surface of the mesa structure on the insulating film; and a second electrode electrically connec

Abstract: To concentrate metals such as gallium from ore which is extracted from mines or used electronic components while suppressing the quantity of waste liquid generated is difficult. A first solid metal compound which contains a metal selected from a group consisting of gallium, indium, germanium, tellurium, and cesium at a first metal content in a mixture of the first solid metal compound is reduced to form a gaseous metal compound, the gaseous metal compound is oxidized to form a second solid metal compound, and the second solid metal compound is collected at a second metal content which is higher than the first metal content.