Surface characterization of nitride structures on Cu(001) formed by N2 ion implantation

L.J. CRISTINA;; R.A. VIDAL; J. FERRÓN.

Conferencia; ACSIN 10. 10th Internacional Conference on Atomically Controlled Surfaces, Interfaces and Nanostructures.; 2009

By means of Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), Low Energy Ion Spectrometry (LEIS) and Angle Resolved UV Photoelectron Spectroscopy (ARUPS) techniques, we studied the process of low energy N2+implantation and annealing of a Cu(001) surface, a proposed system for self-assembled nanostructures. We characterized the N diffusion features as a function of the substrate temperature (AES) and we followed the chemical state of N and Cu along the annealing process (XPS). Taking advantage of the surface sensitivity and elemental detection capability of LEIS, we gained insight about the surface structure formation process. We found that under annealing (500K < T < 700K) N migrates to the surface. The formed compound decomposes for temperatures above 700K. Keeping the substrate temperature constant, N binding energy shifts non-monotonously along the process, pointing out that the N-Cu bonding environment depends on the atomic rearrangement and on the N amount. LEIS measurements shows that N locates on the fourfold hollow site of the Cu(001) surface. Our results are compatible with a c(2x2) ordering, but at the same time we cannot disregard that some N atoms are either located on other fourfold hollow sites in c(1x1) sites or substituting Cu atoms. Finally, ARUPS measurements show that N implantation opens a gap along the 100 direction.