FACULTY OF ENGINEERINGDEPARTMENT OF METALLURGICAL AND MATERIALS ENGINEERING


Bengisu Yaşar

Bengisu Yaşar
Room No: 
D-209
Telephone: 
+90 (312) 210-5842
Fax: 
+90 (312) 210-2518
E-mail: 
byasar@metu.edu.tr
Education: 

B.Sc., Middle East Technical University, Metallurgical & Materials Eng. (2014)

B.Sc. Minor, Middle East Technical University, Solid State Physics in the Department of Physics (2015)

M.Sc., Middle East Technical University, Metallurgical & Materials Eng. (2014- )

Research Interests: 
  • Advanced Characterization Techniques (XRD, SEM,TEM)
Assisted Courses / Laboratories: 
  • Thermodynamics of Materials (METE 203),(METE 501)
  • Phase Equilibria (METE 301)
Thesis / Research Information: 

Cd1-x Znx Te is a room temperature semiconductor which used in medical imaging,industrial process monitoring, nuclear safeguards (Radiation detectors, solar cells , electro-optic modulators etc.).It can be produced in two different grades , based on the amount of Zinc content in the crystal , which are detector grades and substrate grades. When x is 0.04 it is used as epitaxial substrates of Hg 1-y Cd y Te ,which is a material that is used especially for the thermal cameras, ; when x is 0.05-0.2 it can be used for the fabrication of high performance detectors. The reason why CZT crystals are preferred in medical, scientific, industrial areas as a detector is based on its attractive electric and chemical properties. It has high atomic number (Z) for efficient radiation–atomic interactions, large enough bandgap for high resistivity and low leakage current. Also its energy resolution is much superior to scintillator detectors and preferred in energy dispersive systems.In the case of the substrate grades of CZT ,due to its very close lattice parameter and similar thermal expansion coefficient with the HgCdTe,CZT is used as a substrate for the production of MCT epilayer by MBE growth techique. Although it has highly matched lattice parameters, it has proven that any defects in the CZT substrate effect the MCT layer so that detector performance is deteriorated. For this reason the defects formed during crystal growth, post-growth processes should be minimized. During this project the CZT crystal is produced by Vertical Bridgman Furnace in which the crystal is melted before it is directionally solidified with a rate of 1-10K/cm and with a very small withdrawal rate (1-1.5mm/hr).After the ingot is produced , it should be sliced and characterized so that defect free (211) oriented sample is obtained.For the characterization of CZT the advanced techniques which are transmission electron microscope(TEM),scanning electron microscope (SEM) and x-ray diffraction (XRD) will be used.