Tcnq Grown On Cu (001): Its Atomic And Electronic Structure Determination

In this paper we have resolved by means of "in situ" X-ray diffraction studies the atomic structure of the TCNQfilms from 0.4 to 17 ML thickness grown on Cu(001) substrate. The film grown at low temperature, is a well crystallized and well oriented single phase. The TCNQ film has a (020) orientation. The electronic properties of the film have been studied by means of XPS and UPS spectroscopies. The measured electronic density has been compared to the theoretical ab-inito calculations. In this paper we have studied the structural and electronic properties of relatively thick films of TCNQ on Cu(100). Our results demonstrate that the strong charge transfer between the metallic substrate and the first layer of TCNQ molecules have important consequences for the film electronic and structural properties of films even as thick as 17 ML. From the structural point of view, the films grow with a well-defined (020) orientation that matches the modified molecular structure of the first layer. This first monolayer structure was previously explained in literature in terms of adsorbate-induced reconstruction of the Cu surface. From the electronic point of view, charge transfer leads to band bending and determines that barrier for electron injection across the metal/organic interface.