A semiconductor device includes a first substrate, an insulation layer, and a first electrode. The first substrate contains a first semiconductor material. The insulation layer includes a first surface, a second surface, and a third surface. The first electrode includes a fourth surface, a fifth surface, and a sixth surface, and contains a porous first conductive material. The second surface and the fifth surface configure the same surface. The third surface faces the sixth surface. A distance between the first surface and the first substrate is less than a distance between the second surface and the first substrate. A distance between the fourth surface and the first substrate is less than a distance between the fifth surface and the first substrate.