Nordheim Tunneling Research Articles

The Resistive Switching Characteristics and Electrical Conduction Mechanisms of Memory Devices Based on Nanocomposite

The resistive switching memory device based on nanocomposites has become a potential candidate in the data storage field. Understanding resistive switching characteristics and electrical conduction mechanisms may support the appropriate way to fabricate and control the operation of a device. In this study, a capacitor-like structure using PVA-ZnO as an insulator layer was fabricated by a solution method. The crystalline structure, morphology, and absorption spectrum of ZnO nanoparticles were revealed respectively. The resistive switching effect was observed with the ON/OFF ratio of 0.5´102, high endurance, excellent retention and the electrical transport mechanisms were followed by the SCLC and Ohmic’s law in the low resistance state and Flower- Nordheim tunneling in the high resistance state. The resistive switching mechanism was contributed by the oxygen vacancies in ZnO nanoparticles and the oxygen ions in the bottom electrode.

Fowler--Nordheim Tunneling at Sharp-Shaped Floating Gate Structure Modeled as Triangular Electrode

Fowler--Nordheim Tunneling at Sharp-Shaped Floating Gate Structure Modeled as Triangular Electrode

Silicon-based hot electron emitting substrate with double tunneling

We propose a novel silicon structure, Hot Electron Emitting Substrate (HEES), which exhibits important effect of repeated tunneling at two different voltage ranges, which we refer to as double tunneling. In ambient atmosphere and room temperature, the [Formula: see text]–[Formula: see text] characteristic of HEES shows two current peaks during voltage sweep from 2 to 15 V. These two peaks are formed by the Fowler–Nordheim (FN) tunneling effect and tunneling diode mechanism, respectively.

Electrical characteristics of multilayered HfO2-Al2O3 charge trapping stacks deposited by ALD

Electrical and charge trapping properties of atomic layer deposited HfO2-Al2O3 multilayer stacks with two different Al2O3 sublayer thicknesses were investigated regarding their implementation in charge trapping non-volatile memories. The effect of post deposition annealing in oxygen at 600°C is also studied. The decreasing Al2O3 thickness increases the stack's dielectric constant and the density of the initial positive oxide charge. The initial oxide charge increases after annealing to ∼6×1012 cm-2 and changes its sign to negative for the stacks with thicker Al2O3. The annealing enhances the dielectric constant of the stacks and reduces their thickness preserving the amorphous status. Nevertheless the annealing is not beneficial for the stacks with thicker Al2O3 as it considerably increases leakage currents. Conduction mechanisms in stacks were considered in terms of hopping conduction at low electric fields, and Fowler- Nordheim tunnelling, Schottky emission and Poole-Frenkel effect at higher ones. Maximum memory windows of about 12 and 16V were obtained for the as-grown structures with higher and lower Al2O3 content, respectively. In latter case additional improvement (the memory window increase up to 23V) is achieved by the annealing.

Band-to-Band Hot Hole Erase Mechanism of p-Channel Junctionless Silicon Nanowire Nonvolatile Memory

In this paper, p-channel junctionless (JL) silicon-oxide–nitride-oxide–silicon (SONOS)-type nonvolatile memory (NVM) devices with gate-all-around (GAA) nanowire (NW) structure by using silicon-nanocrystal for the charge-trapping layer are presented. The devices exhibited good erase efficiency and excellent retention behavior and can be used in system-on-panel and 3-D-stacked flash memory applications. In addition, a band-to-band hot hole (BBHH) method for erasing is proposed and compared with the Fowler–Nordheim (FN) tunneling method. Because FN erasing requires a high gate voltage, BBHH erasing, which requires a low voltage, can increase the service life of the memory. Channel hot electron and band-to-band hot electron were used for programming and yielded low programming efficiency for the p-channel JL GAA NW NVM devices because of a lack of electron carriers. The program/erase efficiency is related to the channel type in JL NVM devices.

Fowler–Nordheim Tunnelling Contribution in AlGaN/GaN on Si (111) Schottky Current

ABSTRACTAlGaN/GaN heterojunction with Schottky metal contact can be modelled with two back-to-back diodes. The forward-biased diode between metal and AlGaN barrier acts at the onset of current with positive bias. Fowler– Nordheim tunnelling is mainly responsible for the electron transport at the low positive bias level. Downward energy band bending of AlGaN barrier with further positive voltage reduces the tunnelling probability due to lowering of the barrier height of the first diode, causing a dramatic change in the current.

A simple method for determination of Fowler–Nordheim tunnelling parameters

A simple technique for extracting the Fowler–Nordheim (FN) tunnelling parameters is proposed. It consists of measuring the Drain-Source current of a floating gate transistor while a linear ramp voltage is applied to a simple injector structure attached to the transistor's floating gate. Such a test device is fabricated using a standard CMOS process. The parameters obtained can be used in a freely available electrical simulator as SPICE3f5 (NGSPICE), but in general it can be easily adapted to other SPICE-like programs. We describe the technique step-by-step and a comparison is made of simulated and measured FN tunnelling parameters, for a floating gate transistor with tunnelling injectors. A good agreement has been found between experimental and simulated data.

Nanoencapsulation and Stabilization of Single-Molecule/Particle Electronic Nanoassemblies Using Low-Temperature Atomic Layer Deposition

This work addresses a significant challenge in engineered molecular systems regarding both understanding and controlling the stability of molecule/nanoparticle nanostructures under ambient exposure. Results deal specifically with molecular electronic junctions, where electronic contacts and transport are known to be sensitive to sample history and ambient exposure. We demonstrate that low-temperature atomic layer deposition can gently encapsulate and stabilize molecular electronic junctions, making it feasible to handle and transport junctions in air for many days with minimal change in electronic conduction. These findings indicate the potential for long-term stability of advanced synthetic nanoparticle/molecule nanoconstructs. For this study, conductivity through nanoparticle/molecule/nanoparticle junctions is analyzed and found to be consistent with nonresonant charge tunneling through a single or a small number of oligomeric phenylene ethynylene molecules in the electrical junction. The conductivity was stable in vacuum and inert gas, but under ambient exposure, the current initially decreased, then increased rapidly, followed by a slower rise, reaching a value exceeding 10 times larger than initially measured. After encapsulating functional devices using atomic layer deposition of aluminum oxide thin films at 30−50 °C, the junction showed conductance similar to the precoated values, and the current remained unchanged after more than 15 days under ambient exposure. The presence of the molecule junction after encapsulation was confirmed by the observed transition to Fowler−Nordheim tunneling and analysis of junction breakdown at high fields. The high conformality, precise thickness control, and low-temperature compatibility of the atomic layer deposition method make it uniquely qualified to stabilize and protect molecular junctions and systems.

Work Function Characterization of TaSiN and TaCN Electrodes Using CV, IV, IPE and SKPM

Work function of TaSiN (TaCN) films on HfO2 or SiO2 gate dielectrics is investigated for the first time using a combination of Capacitance-Voltage, Fowler- Nordheim tunneling, internal Photoemission, and scanning Kelevin probe microscopy methods, which consistently show ~0.2 eV work function difference between these two metals. These results indicate that Fermi-level pinning on HfO2 is not an issue for these metal systems. SKPM gives qualitative results. Beveled structure and complicated modeling are needed for the potential quantitative application of SKPM in metal/high-k systems. The capacitive-voltage and internal photoemission measurements were performed on the same test structures. Work function values extracted from these two methods agree well.

Porous silicon light-emitting diodes – mechanisms in the operation

Abstract Although electroluminescence (EL) in porous silicon (PS) had been demonstrated by a number of groups, there is lack of a generally accepted, consistent explanation of the conditions for light emission. In this work the mechanisms involved are discussed by studying the temperature-dependent behaviour of PS light-emitting diode (LED) devices fabricated in anodised p-type and n-type Si substrates. The indium tin oxide (ITO)–porous Si–crystalline Si structure was characterised in vacuum by recording the I – V characteristics and the simultaneous light emission at different temperatures. The temperature dependence originates from the porous–single crystal heterojunction and the conduction in the structure, while occurrence of EL requires the dominance of Fowler–Nordheim (FN) tunneling in PS. By identifying the different temperature-dependent I – V regions, an equivalent circuit for the PS LEDs will be proposed.