Curriculum Vitae of Dr. Alaa Dahshan
* Dr Alaa Dahshan
Family name
Dahshan
First name
Alaa El Dein Ibrahim
Sex
Male
Professional title
Lecturer
Country
Egypt
Citizenship
Egyptian
Academic
Ph. D. Physics, Faculty of Science, Assiut University 24 - 09 – 2006
degrees
M.Sc. Physics, Faculty of Science, Assiut University 10 - 05 – 2003
B.Sc. Physics, Faculty of Science, Helwan University 28 – 05 - 1995
Address
Physics Department - Faculty of Science - Suez Canal University, Port Said
, Egypt.
Occupations
Demonstrator
03-01-1998 to 10-05-2003, Faculty of Science, Assuit University
Assistant lecturer 10-05-2003 to 07-04-2005, Faculty of Science, Assuit University
Assistant lecturer 08-04-2005
to
27-11-2006,
Faculty of Education Suez Canal
University
Lecturer
28-11-2006 to 10-03-2008, Faculty of Education Suez Canal University
Lecturer
11-03-2008 till now, Faculty of Science, Suez Canal University
E-mail
adahshan73@gmail.com , alaadahshan@yahoo.com
URL
http://docs.google.com/View?docid=dgv74v6c_0g4w7jwjb
* Home institution
Name
Physics Department - Faculty of Science - Suez Canal University.
Address
Physics Department - Faculty of Science - Suez Canal University, Port
Said , Egypt.
Telephone
+2-066-3657602
Telefax
+2-066-3657602
* References
1. Prof. Dr. A. H. Moharram Head of Physics Department, Faculty of
University, Assiut, Egypt.
e-mail : mohar200@yahoo.com
Science, Assiut
2. Prof. Dr. A. A. Othman
Physics Department, Faculty of Science, Assiut University,
Assiut, Egypt.
e-mail : aaelho@yahoo.com
3. Dr. M. El-Metwally
Head of Physics Department, Faculty of Science, Suez Canal
University, Port Said , Egypt.
e-mail: melmetwally@yahoo.com
* Field of Study
The main research interests include:

Synthesis and characterization of a wide range of bulk and thin film of new amorphous
semiconductors.

Study the optical, electronic and photoelectrical properties of thin films of amorphous
semiconductors.

Preparing the bulk glasses by the melt quench technique and thin films by thermal
evaporation of the bulk samples.

Study the compositional dependence of the complex refractive index (nc = n – ik) and
other optical constants of the amorphous thin films.

Study the thermal stability and crystallization kinetics of the bulk glasses by the
differential scanning calorimetry (DSC).
* Publications
1. Effect of MoO3 additions on the thermal stability and crystallization kinetics of PbO-Sb2O3As2O3 glasses, K. A. Aly, A. Dahshan, Yasser B. Saddeek, accepted in Thermal Analysis
and Calorimetry (2009).
2. Determination of the thickness and optical constants of amorphous Ge-Se-Bi thin films, A.
Dahshan, K. A. Aly, Philos. Mag. 89:12 (2009) 1005.
3. Thermal stability of Ge-As-Te-In glasses, K. A. Aly, A. Dahshan, F. M. Abdel-Rahim, J.
Alloys and Comp. 470 (2009) 574.
4. Optical constants of thermally evaporated Se-Sb-Te films using only their transmission
spectra, K. A. Aly, H. H. Amer, A. Dahshan, Mater. Chem. Phys. 113 (2009) 690.
5. Compositional dependence of the optical constants of amorphous GexAs20Se80-x thin films,
A. Dahshan, H. H. Amer, K. A. Aly, J. Phys. D: Appl. Phys. 41 (2008) 215401.
6. Thermal stability and activation energy of some compositions of Ge-Te-Cu chalcogenide
system, A. Dahshan, K. A. Aly, M. T. Dessouky, Philos. Mag. 88:16 (2008) 2399-2410.
7. Optical constants of new amorphous As-Ge-Se-Sb thin films, A. Dahshan, K. A. Aly, Acta
Mater. 56 (2008) 4869.
8. Thermal stability and crystallization kinetics of new As-Ge-Se-Sb glasses, A. Dahshan, J.
Non-Cryst. Solids 354 (2008) 3034.
9. Characterization of new quaternary chalcogenide As-Ge-Se-Sb thin films, A. Dahshan,
K. A. Aly, Philos. Mag. 88:3 (2008) 361-372.
10. Compositional dependence of the optical properties of
amorphous
Se 100-xTex thin
films, K. A. Aly, A. Dahshan, A. M. Abousehly, Philos. Mag. 88:1 (2008) 47-60.
11. Photoconductivity of amorphous As–Se–Sb thin films, A. Dahshan, H. H. Amer, A. H.
Moharram, A. A. Othman, Thin Solid Films 513 (2006) 369.
12. Experimental Characterization of Amorphous As-Se-Sb Alloys, A. H. Moharram, A. A.
Othman, H. H. Amer, A. Dahshan, J. Non-Cryst. Solids 352 (2006) 2187.
13. Non-isothermal crystallization kinetics study on new amorphous Ga20S75Sb5 and
Ga20S40Sb40 chalcogenide glasses, A. A. Othman, H. H. Amer, M. A. Osman, A. Dahshan,
J. Non-Cryst. Solids 351 (2005) 130.
14. Annealing dependence of optical properties of Ga20S75Sb5 and Ga20S40Sb40 thin
films, A. A. Othman, M. A. Osman, H. H. Amer, A. Dahshan, Thin Solid Films 457
(2004) 253.
15. Reversible Photodarkening in Amorphous Ga20S75Sb5 and Ga20S40Sb40 Thin Films,
A. A. Othman, H. H. Amer, M. A. Osman, A. Dahshan, Radiation Effects & Defects
in Solids 159 (2004) 659.
* Conferences and Courses
1. 10th International school and workshop of crystallography on Role of Synchrotron
Radiation in Advancement of Materials Sciences, 1-5 February 2009, Gulf of Suez (Red
Sea), Ain Soukhna, Egypt.
2. 8th International workshop of crystallography on Recent Advances in X-ray Powder
Diffraction, 27 November - 2 December 2004, Assiut, Egypt.
3. Workshop on Materials Science and Radiation Physics, December 2003, Assiut, Egypt.
4. Course in Material Analysis, International Quality Network Project "Technology of
New Materials" 72 hours, winter semester 2002, University of Applied Science, Berlin,
Germany.
5. Course in Composite Materials, International Quality Network Project "Technology of
New Materials" 96 hours, winter semester 2002, University of Applied Science, Berlin,
Germany.
6. Second International Spring School on Current Activities of Materials Science, April
2000, Assiut, Egypt.
7. First International Spring School on Current Activities of Materials Science, April
1999, Assiut, Egypt.
* Ph.D. Thesis
" Photo-Induced Changes in Arsenic Selenium Antimony Alloys"
24 - 09 - 2006
Abstract:
Bulk As30Se70-xSbx (where x = 2.5, 5, 7.5, 10, 12.5, 15 & 17.5 at. %) alloys were
prepared from As, Se and Sb elements with high purity (5N) using the melt quench technique.
Thin films were prepared by thermal evaporation of small ingot pieces onto glass
substrates (microscope slides). The thermal evaporation process was performed inside a
coating (Edward 306E) system, at a pressure of approximately 10-5 Torr. During the deposition
process (at normal incidence), the substrates were suitably rotated in order to obtain
homogenous films. Film thickness was controlled using a quartz crystal (Edward FTM5)
thickness monitor to be in the range 300-320 nm.
It can be readily seen that the composition As30Se60Sb10 represents the so-called
stoichiometric composition, with this composition as a reference, glasses with Se content of
more than 60 at.% can be called Se-rich glasses and those with Se content of less than 60
at.% can be called As-rich glasses.
Non-isothermal differential scanning calorimetric (DSC) measurements of the asquenched As30Se70-xSbx glasses reveal that the characteristic temperatures e.g. the glass
transition temperature (Tg), the temperature corresponding to the maximum crystallization rate
(Tp) are strongly dependent on heating rate and Sb content. Upon heating, these glasses show a
single glass transition temperature (Tg). The activation energies of crystallization (Ec) were
evaluated by two different methods. The crystallization data were examined in terms of recent
analysis developed for non-isothermal conditions. Decreasing the thermal stability of the
As30Se70-xSbx specimen by increasing Sb content is responsible for occurring the amorphouscrystalline process at lower temperatures.
Increasing Sb content was found to affect the optical properties of these films. Nondirect electronic transition was found to be responsible for the photon absorption inside the
investigated films. Replacement of selenium by antimony atoms results in a monotonic
decrease in the band gap of As30Se70-xSbx thin films. The chemical bond approach has been
applied successfully to interpret the decrease of the glass optical gap with increasing Sb
content. Binary As2Se3 and Sb2Se3 phases are the main components of the stoichiometric
As30Se60Sb10 composition.
Reversible photodarkening upon illumination with UV light at 300 K of well annealed
As30Se70-xSbx thin films was studied and discussed in the light of current models of
photodarkening. The photo-induced red shift of the optical band gap showed a minimum value
at the stoichiometric As30Se60Sb10 composition. The shift of the optical absorption edge was
not parallel but always accompanied by a decrease in the slope of the Tauc curve, indicating
an increase in disorder.
The effect of replacement of selenium by antimony atoms on the steady state and the
transient photoconductivity of the thermally evaporated As30Se70-xSbx (x = 2.5, 5, 7.5, 10, 12.5,
15 & 17.5 at. %) thin films was studied. The compositional dependence of the steady state
photoconductivity at room temperature shows that the photoconductivity increases while the
photosensitivity
decreases
with
increasing
the
antimony
content.
The
transient
photoconductivity shows that the lifetime of the carrier decreases with increasing the light
intensity. This decrease suggests that the photoconductivity mechanism in our samples was
controlled by the transition trapping processes.