Electrical Characterization of Al/Ta2O5/Al Structures Grown by Electron Beam Deposition

I.S. Yahiaa, b and A.A.M. Faragc aDepartment of Physics, Center of Excellent for Advanced Materials Research, Faculty of Science, King Khalid University, P.O. Box 9004, Abha, Saudi Arabia bNano-Science&Semiconductor Labs., Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt cThin Film Laboratory, Department of Physics, Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt

Received: April 28, 2013; In final form: February 20, 2014

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We report study of current density-voltage (J-V) and capacitance-voltage (C-V) characteristics of Al/Ta2O5/Al metal-insulator-metal structures prepared by electron beam deposition. At low bias voltages the J-V characteristics of Al/Ta2O5/Al structures show ohmic conduction. At higher voltages the conductivity becomes limited by space charge. The space charge limited conductivity is due to carrier trap centers located within the energy gap of Ta2O5. The distribution of the trap appears to be exponential above the valence band. Basing on the comparison of the measured temperature dependences of the current density with the theoretical model one can determine important material parameters, such as the trap density. The density of states at the Fermi level N(EF) for the Ta2O5 film is found to be 2.75 × 1019 eV-1 cm-3. The capacitance-voltage-temperature (C-V-T) characteristics of Al/Ta2O5/Al structures were carried out in the bias range -5 to +5 V and at temperatures from 300 to 550 K. The capacitance of Al/Ta2O5/Al structures increases with the increasing temperature.

DOI: 10.12693/APhysPolA.125.1191 PACS numbers: 77.84.Bw, 77.55.-g, 81.10.Bk, 85.30.Kk, 85.30.-z