Investigation of the impact of insulator material on the performance of dissimilar electrode metal-insulator-metal diodes

• Published in: Journal of applied physics Vol. 116; no. 2
• Main Authors: Alimardani, Nasir, King, Sean W., French, Benjamin L., Tan, Cheng, Lampert, Benjamin P., Conley, John F.
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 14.07.2014
• Subjects: ALUMINIUM OXIDES; Aluminum oxide; AMORPHOUS STATE; Applied physics; ASYMMETRY; Atomic layer epitaxy; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRYSTAL DEFECTS; Defects; Dissimilar materials; Dissimilar metals; ELECTRIC POTENTIAL; ELECTRODES; Electron affinity; Electron energy loss spectroscopy; EMISSION; Energy dissipation; Energy gap; Energy levels; Energy measurement; ENERGY-LOSS SPECTROSCOPY; EV RANGE; Hafnium oxide; HAFNIUM OXIDES; Insulators; Linearity; METALS; MIM diodes; NIOBIUM OXIDES; Position measurement; Reels; REFLECTION; Silicon dioxide; SILICON OXIDES; TANTALUM OXIDES; THIN FILMS; TRAPS; TUNNEL EFFECT; VACANCIES; ZIRCONIUM OXIDES
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4889798

The performance of thin film metal-insulator-metal (MIM) diodes is investigated for a variety of large and small electron affinity insulators using ultrasmooth amorphous metal as the bottom electrode. Nb2O5, Ta2O5, ZrO2, HfO2, Al2O3, and SiO2 amorphous insulators are deposited via atomic layer deposition (ALD). Reflection electron energy loss spectroscopy (REELS) is utilized to measure the band-gap energy (EG) and energy position of intrinsic sub-gap defect states for each insulator. EG of as-deposited ALD insulators are found to be Nb2O5 = 3.8 eV, Ta2O5 = 4.4 eV, ZrO2 = 5.4 eV, HfO2 = 5.6 eV, Al2O3 = 6.4 eV, and SiO2 = 8.8 eV with uncertainty of ±0.2 eV. Current vs. voltage asymmetry, non-linearity, turn-on voltage, and dominant conduction mechanisms are compared. Al2O3 and SiO2 are found to operate based on Fowler-Nordheim tunneling. Al2O3 shows the highest asymmetry. ZrO2, Nb2O5, and Ta2O5 based diodes are found to be dominated by Frenkel-Poole emission at large biases and exhibit lower asymmetry. The electrically estimated trap energy levels for defects that dominate Frenkel-Poole conduction are found to be consistent with the energy levels of surface oxygen vacancy defects observed in REELS measurements. For HfO2, conduction is found to be a mix of trap assisted tunneling and Frenkel-Poole emission. Insulator selection criteria in regards to MIM diodes applications are discussed.