Substrate and light emitting device

A light emitting device comprising:

• a substrate;
• and
• a light source disposed above the substrate, wherein:
• the substrate comprises:
• a first member having a through hole extending from an upper surface to a lower surface thereof, and
• a second member disposed inside the through hole, and
• the second member includes:
• a first region containing graphite, and located at a position overlapping the light source in a top view,
• a second region located outward of the first region in the top view, containing graphite and a thermally conductive material that contains at least one of a metal or a ceramic, and having a volume fraction of the graphite lower than a volume fraction of the graphite in the first region, and
• a third region located outward of the second region in the top view, containing a thermally conductive material that contains at least one of a metal or a ceramic, and having a volume fraction of the thermally conductive material higher than a volume fraction of the thermally conductive material in the second region.