Electrical characteristics and conduction mechanisms of amorphous subnanometric Al 2 O 3 –TiO 2 laminate dielectrics deposited by atomic layer deposition

• Published in: Applied physics letters 2016-11, Vol.109 (20)
• Main Authors: Kahouli, Abdelkader, Lebedev, Oleg, Dao, Vu Hung, Elbahri, Marwa Ben, Prellier, Wilfrid, Luders, Ulrike
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Material chemistry; Physics
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4967534

Electric conduction mechanisms of amorphous Al2O3/TiO2(ATO)-laminates deposited by atomiclayer deposition with sub-nanometer individual layer thicknesses were studied in a large temperaturerange. Two characteristic field regions are identified. In the low field region (E0.31 MV/cm), theleakage current is dominated by the trap-assisted tunneling through oxygen vacancies occurring in theTiO2, while in the high electric field region (E>0.31 MV/cm) the Poole Frenkel (PF) hopping is theappropriate conduction process with energy levels depending on the temperature and the electric field.It is shown that the PF potential levels decrease with the applied ATO field due to the overlapping ofthe Coulomb potential. Amorphous ATO-laminates show the presence of two intrinsic potentialenergy levels/i, which are 0.18 eV for low temperature region and 0.4 eV at high temperature region.Oxygen vacancies are the main origin of traps, which is consistent with the principal mechanisms forleakage in ATO-laminates.