A submount for an electronic device includes a substrate formed of a bulk material including first and second major surfaces on opposite sides of the substrate, a surface insulating layer on the first major surface of the substrate, and a die attach pad on the surface insulating layer. The die attach pad may be electrically insulated from the substrate by the surface insulating layer. The submount further includes a heatsink contact pad on the second major surface of the substrate, and a thermal conduction member extending from the second major surface of the conductive semiconductor substrate through the substrate toward the first major surface of the substrate. The thermal conduction member has a higher thermal conductivity than a thermal conductivity of the bulk material of the substrate.