SCANNING ELECTRON MICROSCOPY(SEM)
METHODS IN STUDY OF MICRO OBJECTS
GAQA S.G.
MANAKA M.C.
MOIPOLAI T.B.
THABETHE B.S.
SUPERVISOR: O.ORELOVITCH
FLEROV LABORATORY OF NUCLEAR
REACTIONS, CENTER OF APPLIED PHYSYSCS
LAYOUT
 AIMS AND OBJECTIVES
 INTRODUCTION
 GENERAL VIEW OF SEM JSM-840
 HOW SEM WORKS
 GENERAL VIEW OF ION SPUTTER
 EXPERIMENTAL PROCEDURE
 RESULTS AND DISCUSSION
 CONCLUSION
AIMS AND OBJECTIVES
 Learning the principles of SEM
 Study the methods of sample investigations with
the use of SEM
INTRODUCTION

What is SEM(Scanning electron microscopy)
SEM is a type of electron microscope that images the sample by
scanning it with high energy beam of electrons .
The signals obtained from electron-sample interaction reveal
information about the sample including external morphology
(texture), chemical composition, and crystalline structure and
orientation of materials making up the sample.

Why SEM
.
SEM is indispensable when observation of objects with the size less
than the wavelength of light is required
GENERAL VIEW OF SEM JSM-840
HOW DOES SEM WORK
 TV signal from SEM is
transferred to analogdigital converter (ADC)
 It is then processed by
special system and
shown on the computer
monitor as digital
picture in PCX format.
ION SPUTTER
•The specimen stage
with the membrane
samples are placed
on the specimen
stand under the bell
jar
• The membrane
samples are covered
with gold by setting
the air pressure
under the bell jar to
0.2 torr, voltage to
1.2kV and the current
to 10 mA for two
minutes
EXPERIMENTAL PROCEDURE
 The specimen stage was cleaned with acetone.
 The membrane samples were mounted on the
specimen stage using silver conductive glue.
 The specimen stage together with the mounted
membrane samples were placed on the ion sputter to
cover with gold.
 The membrane samples were placed in the scanning
electron microscope for characterization.
RESULTS AND DISCUSSION
 Without covering there
is a surface charge
 It is due to the surface
resistance of the polymer
membrane to the
secondary electrons.
 The surface of the
sample is not thermo
conductive.
CONTINUED
 With covering there is
less surface charge
 the surface of sample is
electro conductive to
minimize charging from
the incident beam
 the surface of sample is
thermo conductive to
minimize local heating
 the material of sample has
a high atomic number to
increase the coefficient of
secondary electrons .
CONTINUED
 With tilting a better
view of the topography is
achieved
CONTINUED
 A more better view of the
surface and pores is
achieved at increased
tilting angles.
METAL MEMBRANE
 Metal membrane
 Conductive
 Surface topography can
still be achieved without
covering with gold.
SODIUM CHLORIDE
• Covered with gold by
rotating the sample
twice at an angle of 90
degrees
CONCLUSION
 The principles of SEM and methods of sample
preparation were learned
 Membrane samples covered with gold showed no
surface charge and the uncovered membrane samples
showed a surface charge
 A better view of the topography was achieved when
tilting the sample.
ACKNOWLEDGEMENTS
 NRF and DST for funding
 Organisers of the student summer practice
 JINR(University Centre) for the study opportunity
 Project supervisor, Dr. Oleg Orelovitch for his
unending support through out the project
REREFENCE
 D. Pease, Histological Techniques for Electron
Microscopy, Academic Press, New York and London,
1960
 J. Goldstein, H. Yakowetz, PRACTICAL SCANNING
ELECTRON MICROSCOPY, Plenum Press, New York
and London, 1975
THANK YOU
QUESTIONS