A 3D device including: a first layer including first transistors, the first layer overlaid by at least one interconnection layer; a second layer including second transistors, the second layer overlaying the interconnection layer; a plurality of electrical connections connecting the second transistors with the interconnection layer; and at least one thermally conductive and electrically non-conductive contact, where the at least one thermally conductive and electrically non-conductive contact thermally connects the second layer to a top or bottom surface of the 3D device.