Effect of the composition on the bandgap width of high-κ MexTiyOz (Me = Hf, Ta, Sr) layers

The influence of phases and phase's boundaries of TiO 2 and Ta 2 O 5 in the dielectric and electric response of TiTaO (100 nm thick) elaborated by RF magnetron sputtering was highlighted by complex impedance spectroscopy. Dielectric and electric modulus properties were studied over a wide frequency range (0.1-10 5 Hz) and at various temperatures (−160 to 120 • C). The diagram of Argand (ε ′′ versus ε ′ ) shows the contribution of phases, phases' boundaries and conductivity effect on the electric response of TiTaO thin films. Moreover, the resistance of the material decreases when the temperature increases, thus the material exhibits a negative temperature coefficient of resistance. The electric modulus plot indicates the presence of two peaks of relaxation. The first relaxation process appears at low temperature with activation energy of about 0.22 eV and it is related to the first ionization energy of oxygen vacancies. The second relaxation process appears at high temperature with activation energy of about 0.44 eV. This second peak is attributed to the Maxwell-Wagner-Sillars relaxation. The plots of the complex dielectric modulus and the impedance as a function of frequency allow concluding to a localized relaxation due to the long-range conductivity in the TiTaO film.

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Effect of the composition on the bandgap width of high-κ MexTiyOz (Me = Hf, Ta, Sr) layers

Cited by 4 publications

References 15 publications

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