An apparatus, method and thin-film structure for producing a blackbody spectrum is disclosed. A first layer of the apparatus is configured to generate heat in response to an applied voltage. A second layer is configured to emit the blackbody radiation spectrum in response to the heat from the first layer. A thermal spreading layer is disposed between the first layer and the second layer. The thermal spreading layer includes a graphene sheet for reducing a spatial variation of the heat in a plane of the thermal spreading layer.