The self-organisation of nitrogen nanostructures at different coverages on
a (100) copper surface is studied by spot profile analysing low energy elec
tron diffraction (SPA-LEED). The existence of two surface states with a dom
ain of coverage leading to coexistence of the two states as already observe
d by scanning tunneling microscopy (STM) [Leibsle and Robinson, Phys. Rev.
B 47 (1993) 15 865; Leibsle et al., Surf. Sci. 317 (1994) 309; Leibsle, Sur
f. Sci. 440 (1999) L835] and low energy electron diffraction (LEED) [Sotto
et al., Surf. Sci. 371 (1997) 36] is confirmed. In the first state, the sur
face is organised in square shape islands separated by bare copper [100] ro
ws. This work shows that the surface periodicity depends on the preparation
of the nitrogen overlayer. When nitrogen coverage is obtained by adsorptio
n with a sample temperature near 320 degrees C, the periodicity does not va
ry with coverage and is found to be equal to 55 +/- 2 Angstrom. At coverage
s below 0.75 +/- 0.05 and if the nitrogen is deposited at room temperature
followed by an anneal at 320 degrees C, during long periods of time, the pe
riodicity evolves to large values (similar to 97 +/- 3 Angstrom). During th
ermal desorption, the long range order with decreasing coverage is maintain
ed but the surface periodicity also evolves continuously to large values (s
imilar to 100 Angstrom). However, a surface periodicity of 55 +/- 2 Angstro
m seems to be a characteristic length of this system. The second surface st
ate corresponds to large c(2 x 2)N domains separated by [110] trenches [Lei
bsle and Robinson, Phys. Rev. B 47 (1993) 15 865; Leibsle et al., Surf. Sci
. 317 (1994) 309; Leibsle, Surf. Sci. 440 (1999) L835]. Nitrogen adsorption
on a (410) stepped face induces a reconstruction into a (810) face with do
uble step height. The complex behaviour of this film growth is discussed in
the light of existing theories about the driving force leading to nanostru
cturation. (C) 2000 Elsevier Science B.V. All rights reserved.