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John F Conley - One of the best experts on this subject based on the ideXlab platform.
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Demonstration of Fowler–Nordheim Tunneling in Simple Solution-Processed Thin Films
2018Co-Authors: Cory K. Perkins, John F Conley, Melanie A. Jenkins, Tsung-han Chiang, Ryan H. Mansergh, Vasily Gouliouk, Nizan Kenane, John F. Wager, Douglas A. KeszlerAbstract:The production of high-quality thin-film insulators is essential to develop advanced technologies based on electron tunneling. Current insulator deposition methods, however, suffer from a variety of limitations, including constrained substrate sizes, limited materials options, and complexity of patterning. Here, we report the deposition of large-area Al2O3 films by a solution process and its integration in metal–insulator–metal devices that exhibit I–V signatures of Fowler–Nordheim electron tunneling. A unique, high-purity precursor based on an aqueous solution of the nanocluster flat-Al13 transforms to thin Al2O3 insulators free of the electron traps and emission states that commonly inhibit tunneling in other films. Tunneling is further confirmed by the temperature independence of device current
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enhancing metal insulator insulator metal tunnel diodes via defect enhanced direct tunneling
Applied Physics Letters, 2014Co-Authors: Nasir Alimardani, John F ConleyAbstract:Metal-insulator-insulator-metal tunnel diodes with dissimilar work function electrodes and nanolaminate Al2O3-Ta2O5 bilayer tunnel barriers deposited by atomic layer deposition are investigated. This combination of high and low electron affinity insulators, each with different dominant conduction mechanisms (tunneling and Frenkel-Poole emission), results in improved low voltage asymmetry and non-linearity of current versus voltage behavior. These improvements are due to defect enhanced direct tunneling in which electrons transport across the Ta2O5 via defect based conduction before tunneling directly through the Al2O3, effectively narrowing the tunnel barrier. Conduction through the device is dominated by tunneling, and operation is relatively insensitive to temperature.
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investigation of the impact of insulator material on the performance of dissimilar electrode metal insulator metal diodes
Journal of Applied Physics, 2014Co-Authors: Nasir Alimardani, Sean W King, Benjamin French, Benjamin P Lampert, John F ConleyAbstract: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 ...
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step tunneling enhanced asymmetry in asymmetric electrode metal insulator insulator metal tunnel diodes
Applied Physics Letters, 2013Co-Authors: Nasir Alimardani, John F ConleyAbstract:The impact of nanolaminate insulator tunnel barriers on asymmetric metal workfunction metal-insulator-insulator-metal (MIIM) devices is investigated. We demonstrate experimentally that bilayer insulators introduce additional asymmetry and can be arranged to either enhance or oppose the asymmetry induced by the asymmetric workfunction electrodes. It is also shown that step tunneling can dominate the I-V asymmetry of M1IIM2 diodes. By combining bilayer tunnel barriers with the standard approach of asymmetric metal electrodes, we are able to achieve low voltage asymmetry and non-linearity exceeding both that of standard single layer asymmetric electrode Metal-Insulator-Metal devices as well as symmetric electrode M1I1I2M1 devices.
Nasir Alimardani - One of the best experts on this subject based on the ideXlab platform.
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enhancing metal insulator insulator metal tunnel diodes via defect enhanced direct tunneling
Applied Physics Letters, 2014Co-Authors: Nasir Alimardani, John F ConleyAbstract:Metal-insulator-insulator-metal tunnel diodes with dissimilar work function electrodes and nanolaminate Al2O3-Ta2O5 bilayer tunnel barriers deposited by atomic layer deposition are investigated. This combination of high and low electron affinity insulators, each with different dominant conduction mechanisms (tunneling and Frenkel-Poole emission), results in improved low voltage asymmetry and non-linearity of current versus voltage behavior. These improvements are due to defect enhanced direct tunneling in which electrons transport across the Ta2O5 via defect based conduction before tunneling directly through the Al2O3, effectively narrowing the tunnel barrier. Conduction through the device is dominated by tunneling, and operation is relatively insensitive to temperature.
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investigation of the impact of insulator material on the performance of dissimilar electrode metal insulator metal diodes
Journal of Applied Physics, 2014Co-Authors: Nasir Alimardani, Sean W King, Benjamin French, Benjamin P Lampert, John F ConleyAbstract: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 ...
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step tunneling enhanced asymmetry in asymmetric electrode metal insulator insulator metal tunnel diodes
Applied Physics Letters, 2013Co-Authors: Nasir Alimardani, John F ConleyAbstract:The impact of nanolaminate insulator tunnel barriers on asymmetric metal workfunction metal-insulator-insulator-metal (MIIM) devices is investigated. We demonstrate experimentally that bilayer insulators introduce additional asymmetry and can be arranged to either enhance or oppose the asymmetry induced by the asymmetric workfunction electrodes. It is also shown that step tunneling can dominate the I-V asymmetry of M1IIM2 diodes. By combining bilayer tunnel barriers with the standard approach of asymmetric metal electrodes, we are able to achieve low voltage asymmetry and non-linearity exceeding both that of standard single layer asymmetric electrode Metal-Insulator-Metal devices as well as symmetric electrode M1I1I2M1 devices.
D Vollhardt - One of the best experts on this subject based on the ideXlab platform.
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mott hubbard transition versus anderson localization in correlated electron systems with disorder
Physical Review Letters, 2005Co-Authors: Krzysztof Byczuk, Walter Hofstetter, D VollhardtAbstract:The phase diagram of correlated, disordered electrons is calculated within dynamical mean--field theory using the geometrically averaged (''typical'') local density of states. Correlated metal, Mott insulator and Anderson insulator phases, as well as coexistence and crossover regimes are identified. The Mott and Anderson insulators are found to be continuously connected.
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mott hubbard transition versus anderson localization in correlated electron systems with disorder
Physical Review Letters, 2005Co-Authors: Krzysztof Byczuk, Walter Hofstetter, D VollhardtAbstract:The phase diagram of correlated, disordered electron systems is calculated within dynamical mean-field theory using the geometrically averaged ("typical") local density of states. Correlated metal, Mott insulator, and Anderson insulator phases, as well as coexistence and crossover regimes, are identified. The Mott and Anderson insulators are found to be continuously connected.
Elias Stefanakos - One of the best experts on this subject based on the ideXlab platform.
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fabrication and characterization of zno langmuir blodgett film and its use in metal insulator metal tunnel diode
Langmuir, 2016Co-Authors: Ibrahim Azad, Manoj K Ram, Yogi D Goswami, Elias StefanakosAbstract:Metal–insulator–metal tunnel diodes have great potential for use in infrared detection and energy harvesting applications. The quantum based tunneling mechanism of electrons in MIM (metal–insulator–metal) or MIIM (metal–insulator–insulator–metal) diodes can facilitate rectification at THz frequencies. In this study, the required nanometer thin insulating layer (I) in the MIM diode structure was fabricated using the Langmuir–Blodgett technique. The zinc stearate LB film was deposited on Au/Cr coated quartz, FTO, and silicon substrates, and then heat treated by varying the temperature from 100 to 550 °C to obtain nanometer thin ZnO layers. The thin films were characterized by XRD, AFM, FTIR, and cyclic voltammetry methods. The final MIM structure was fabricated by depositing chromium/nickel over the ZnO on Au/Cr film. The current voltage (I–V) characteristics of the diode showed that the conduction mechanism is electron tunneling through the thin insulating layer. The sensitivity of the diodes was as high a...
Krzysztof Byczuk - One of the best experts on this subject based on the ideXlab platform.
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mott hubbard transition versus anderson localization in correlated electron systems with disorder
Physical Review Letters, 2005Co-Authors: Krzysztof Byczuk, Walter Hofstetter, D VollhardtAbstract:The phase diagram of correlated, disordered electrons is calculated within dynamical mean--field theory using the geometrically averaged (''typical'') local density of states. Correlated metal, Mott insulator and Anderson insulator phases, as well as coexistence and crossover regimes are identified. The Mott and Anderson insulators are found to be continuously connected.
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mott hubbard transition versus anderson localization in correlated electron systems with disorder
Physical Review Letters, 2005Co-Authors: Krzysztof Byczuk, Walter Hofstetter, D VollhardtAbstract:The phase diagram of correlated, disordered electron systems is calculated within dynamical mean-field theory using the geometrically averaged ("typical") local density of states. Correlated metal, Mott insulator, and Anderson insulator phases, as well as coexistence and crossover regimes, are identified. The Mott and Anderson insulators are found to be continuously connected.