ISSN 1063-7397, Russian Microelectronics, 2007, Vol. 36, No. 3, pp. 164–170. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © A.B. Petrov, R.R. Gallyamov, 2007, published in Mikroelektronika, 2007, Vol. 36, No. 3, pp. 190–197.
The arrival of scanning-probe microscopes has
paved the way for surface science and engineering on a
sub-100-nm scale. The atomic-force microscope
(AFM) occupies a high position among them . The
instrument uses a probe, called the cantilever, interact-
ing with the surface being examined or modiﬁed by
forces of different nature: electrostatic, magnetic, elas-
tic, etc. Owing to this interaction, an image of the sur-
face is generated by scanning the probe along two inde-
pendent coordinate axes, and it is possible to investigate
the forces themselves .
The AFM can be operated in one of three main
modes: contact, semicontact, and noncontact [1, 3].
In contact mode, the probe is in constant contact with
the surface and is subject to a repulsive force of con-
stant magnitude. The probe–surface interaction in this
case is mainly elastic in nature. In semicontact mode,
the cantilever executes periodic vertical vibrations and
is in contact with the surface during a fraction of each
period, typically experiencing an elastic force at the
moment when the contact is established. In noncontact
mode, as its name implies, there is no contact between
the probe and the surface, and the former is acted upon
by an attractive force of van der Waals type. The three
modes of operation imply three different ways of gain-
ing knowledge of the surface and three different types
of feedback signal.
In semicontact mode, information on the surface is
obtained by measuring the amplitude and phase of the
vibration; the former parameter gives data on the sur-
face topography and is used in the feedback loop. An
advantage of this sensing technique is that it allows
nondestructive investigation of soft materials (e.g.,
polymers) because the cantilever does not exert a lateral
force on the surface. On the other hand, one must
address the deformation of such materials by the verti-
The analysis of an AFM image invariably includes
two stages: checking the image for scanning artifacts
 and calculating geometric characteristics of the
surface . In some cases, account must be taken of
tip-induced surface deformation, particularly when
dealing with materials of nonuniform elastic proper-
ties (e.g., metal–polymer nanocomposites) or when
scanning an area less than 100 nm across. The defor-
mation of hard materials during scanning in semicon-
tact mode with zero cantilever damping was studied
by Chizhik et al. .
We here report on an experiment and a computer
simulation concerning the tip-induced deformation of
polymers under semicontact-mode AFM investigation.
Cantilever damping is an important factor in this case.
2. MATERIALS AND METHODS
The material under investigation was commercially
available granular polyethylene with a mean granule
size of 5 mm and a ﬂow-behavior index of 0.3 g/10 min
(made by Ufaorgsintez to the GOST 16337-77 national
standard). The granule density was 0.917–0.921 g/cm
. The material was taken in its original form.
The AFM measurements were made with a Solver
P47 scanning-probe microscope (NT-MDT, Russia)
Polymer Surface Deformation under Semicontact-Mode
A. B. Petrov and R. R. Gallyamov
Bashkir State University, Ufa, Bashkortostan, Russia
Received June 14, 2006
—An experiment and a computer simulation are presented concerning the tip-induced deformation of
polyethylene under semicontact-mode AFM scanning. The dependence is investigated of the deformation on
normalized amplitude of scanning with due regard to cantilever damping. The measured and the simulated
deformation curve are found to agree for sufﬁciently large normalized scanning amplitudes. Otherwise, the
experiment and the simulation diverge. Reasons for this disagreement are suggested within the context of dif-
ferent physical processes inﬂuencing the deformation.
PACS numbers: 68.37.Ps