The results obtained in the study of the morphological modification of a na
tural molybdenum disulphide (MoS2) surface during radio frequency (RF)-oxyg
en plasma treatment are presented. The surface features observed following
etching in oxygen plasmas show a strong dependence on the plasma power and
the corresponding gas pressure. At low powers chemical modification was fou
nd to lead to semi-regular surface disruption at nano-scales, behaviour att
ributed to basal plane contraction of the material resulting from the subst
itution in the surface layers of sulphur by oxygen during etching. This che
mical effect may be promoted by the simultaneous physical bombardment of th
e surface by the relatively energetic particles present in the plasma. Howe
ver, increasing the plasma power appears to reduce the lateral layer-plane
disruption and, instead, leads to a more random, less-structured sputtering
of the surface material. This latter process, depending on the particular
plasma conditions used, leaves irregular-sized disrupted features as humps
or flakes in the observed topography. (C) 1999 Elsevier Science B.V. All ri
ghts reserved.