Change in the electronic states of graphite overlayers depending on thickness

Electronic states of graphite overlayers formed on the TaC(111) surface have been investigated with the use of scanning tunneling microscopy and photoelectron spectroscopy. The graphite film grows on the substrate layer by layer. The thickness of the overlayer has been adjusted precisely to be either one or two monolayers. The physical properties of the monolayer graphite film are modified by chemical bonding at the interface. This interfacial bonding becomes weak upon the formation of the second layer of graphite, which makes the properties of the double-layer graphite film similar to those of bulk graphite.