A device is provided for depositing carbonaceous structures, for example layers in the form of nanotubes or graphene on a substrate, which is supported by a substrate support disposed in a process chamber housing. A process gas can be delivered onto the substrate through gas outlet openings of a gas inlet element disposed in the process chamber housing. The process chamber housing has two opposing walls which each have holding recesses. At least one plate-shaped component is disposed in the process chamber housing. The plate-shaped component has two edge portions directed away from one another that each are inserted respectively in the holding recess of one of the two opposing walls.