Master Thesis Defense: Hamidreza Khassaf
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  • Master Thesis Defense: Hamidreza Khassaf

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Hamidreza Khassaf

Materials Science and Engineering, Master’s Thesis, 2012


 Thesis Jury

Asst. Prof. Burç Mısırlıoğlu (Thesis Supervisor), Asst. Prof. Cleva Ow Yang, Assoc. Prof. Mehmet Ali Gülgün, Asst. Prof. Gözde İnce, Assoc. Prof. Mehmet Yıldız, Assoc. Prof. Ali Koşar


Date &Time: August 1st, 2012 – 08:00

Place: FENS L056


Pure single phase BiFeOand various Gd doping levels were synthesized through a metalorganic route. Quasi-epitaxial (columnar) BiFeO3 film was fabricated on the top of SrTiO3 substrates with preferred orientation. The rectifying properties of Nb:SrTiO3-BiFeO3-Pt structures, in which the BiFeO3 layer was doped with Gd (0 %; 5 %; and 10 %), were investigated by measuring current-voltage characteristic at different temperatures. It was found that the structures show a diode-like behavior with reverse bias for negative polarity and forward bias for positive polarity applied on the top Pt contact. The potential barrier was estimated for negative polarity assuming a Shottky-like thermionic emission with injection controlled by the interface and the drift controlled by the bulk. It was found that the height of the potential barrier is dependent on the Gd doping, being 0.32 eV for zero doping, 0.45 eV for 5 % doping and 0.60 eV for 10 % doping. The result is explained by the partial compensation of the p-type conduction induced by Bi volatility with Gd doping. The Fermi level moves upward as the doping concentration increases leading to a higher potential barrier for holes.