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Barrier height modification in Au/Ti/n-GaAs devices with a $$\hbox {HfO}_{2}$$HfO2 interfacial layer formed by atomic layer deposition
摘要： X-ray photoelectron spectroscopy has been carried out to characterize the surface of the hafnia (HfO2) thin films grown on n-GaAs wafer by atomic layer deposition, and the surface morphology of the HfO2 layer on GaAs has been analysed using atomic force microscopy. The barrier height (BH) values of 1.03 and 0.93 eV (300 K) for the Au/Ti/HfO2/n-GaAs structures with 3- and 5-nm HfO2 interfacial layers, respectively, have been obtained from the I–V characteristics of the devices, which are higher than the value of 0.77 eV (300 K) for the Au/Ti/n-GaAs diode fabricated by us. Therefore, it can be said that the HfO2 thin layer at the metal/GaAs interface can also be used for BH modification as a gate insulator in GaAs metal-oxide semiconductor (MOS) capacitors and MOS field-effect transistors. The ideality factor values have been calculated as 1.028 and 2.72 eV at 400 and 60 K; and as 1.04 and 2.58 eV at 400 and 60 K for the metal–insulating layer–semiconductor (MIS) devices with 3- and 5-nm interfacial layers, respectively. The bias-dependent BH values have been calculated for the devices by both Norde’s method and Gaussian distribution (GD) of BHs at each sample temperature. At 320 K, the (cid:2)b(V ) value at 0.70 V for a 3-nm MIS diode is about 1.08 eV from the (cid:2)b(V ) vs. V curve determined by the GD, and about 0.99 eV at 0.58 V for a 5-nm MIS diode. It has been seen that these bias-dependent BH values are in close agreement with those obtained by Norde’s method for the same bias voltage values.
关键词： metal–insulating layer–semiconductor (MIS) device,Barrier height modification and inhomogeneous,bias-dependent barrier height,temperature-dependent MIS diode parameters,atomic layer deposition (ALD)
更新于2025-09-23 15:23:52
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Switchable Schottky contacts: Simultaneously enhanced output current and reduced leakage current
摘要： Metal-semiconductor contacts are key components of nanoelectronics and atomic-scale integrated circuits. In these components Schottky diodes provide a low forward voltage and a very fast switching rate but suffer the drawback of a high reverse leakage current. Improvement of the reverse bias characteristics without degrading performance of the diode at positive voltages is deemed physically impossible for conventional silicon-based Schottky diodes. However, in this work we propose that this design challenge can be overcome in the organic-based diodes by utilizing reversible transitions between distinct adsorption states of organic molecules on metal surfaces. Motivated by previous experimental observations of controllable adsorption conformations of anthradithiophene on Cu(111), herein we use density functional theory simulations to demonstrate the distinct Schottky barrier heights of the two adsorption states. The higher Schottky barrier of the reverse bias induced by chemisorbed state results in low leakage current; while the lower barrier of the forward bias induced by physisorbed state yields a larger output current. The rectifying behaviors are further supported by nonequilibrium Green's function transport calculations.
关键词： van der Waals forces,Schottky contacts,Schottky barrier height,reverse leakage current,bistable state
更新于2025-09-23 15:23:52
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Reverse bias-dependence of schottky barrier height on silicon carbide: influence of the temperature and donor concentration
摘要： The work deals with the dependences of the Schottky barrier height (SBH) on the reverse bias voltage, temperature and on donor concentration of metal/4H-SiC Schottky diodes. Using the tunneling modeling we have shown that the Schottky barrier height on silicon carbide strongly depends on the reverse bias voltage, temperature and doping concentration. At room temperature, the Schottky barrier height increases with increasing the reverse bias voltage at high doping concentration (about 1016 cm-3), while, at low doping concentration (about 1015 cm-3) the Schottky barrier height decreases with increasing the reverse bias voltage. These behaviors are independent of the Schottky barrier lowering effect. That means other effects occur at the barrier and depend on the reverse applied bias. The barrier height increases with increasing temperature and doping concentration under reverse bias conditions. The barrier heights extracted from the Padovani-Stratton formulas are close to the barrier heights extracted from the Tsu-Esaki formula in particular for the thermionic-field emission.
关键词： Reverse Bias,Silicon Carbide,Extraction,Tunneling,Schottky Barrier Height
更新于2025-09-23 15:22:29
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Current transport mechanism of Mg/Au ohmic contacts to lightly doped n-type <i>β</i> -Ga <sub/>2</sub> O <sub/>3</sub>
摘要： The carrier transport mechanism of Mg/Au ohmic contact for lightly doped β-Ga2O3 is investigated. An excellent ohmic contact has been achieved when the sample was annealed at 400 °C and the specific contact resistance is 4.3 × 10?4 Ω·cm2. For the annealed sample, the temperature dependence of specific contact resistance is studied in the range from 300 to 375 K. The specific contact resistance is decreased from 4.3 × 10?4 to 1.59 × 10?4 Ω·cm2 with an increase of test temperature. As combination with the judge of E00, the basic mechanism of current transport is dominant by thermionic emission theory. The effective barrier height between Mg/Au and β-Ga2O3 is evaluated to be 0.1 eV for annealed sample by fitting experimental data with thermionic emission model.
关键词： effective barrier height,beta-gallium oxide,Mg/Au,ohmic contact,thermionic emission theory
更新于2025-09-23 15:22:29
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PdEr-Silicide Formation and Contact Resistivity Reduction to n-Si(100) Realized by Dopant Segregation Process
摘要： In this paper, we have investigated the PdEr-silicide formation utilizing a developed PdEr-alloy target for sputtering, and evaluated the contact resistivity of PdEr-silicide layer formed on n-Si(100) by dopant segregation process for the first time. Pd2Si and ErSi2 have same hexagonal structure, while the Schottky barrier height for electron (Φbn) is different as 0.75 eV and 0.28 eV, respectively. A 20 nm-thick PdEr-alloy layer was deposited on the n-Si(100) substrates utilizing a developed PdEr-alloy target by the RF magnetron sputtering at room temperature. Then, 10 nm-thick TiN encapsulating layer was in-situ deposited at room temperature. Next, silicidation was carried out by the RTA at 500°C for 5 min in N2/4.9%H2 followed by the selective etching. From the J-V characteristics of fabricated Schottky diode, qΦbn was reduced from 0.75 eV of Pd2Si to 0.43 eV of PdEr-silicide. Furthermore, 4.0x10?8Ωcm2 was extracted for the PdEr-silicide to n-Si(100) by the dopant segregation process.
关键词： contact resistivity,PdEr-alloy target,RF magnetron sputtering,schottky barrier height,silicide
更新于2025-09-23 15:22:29
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Absence of Evidence for Fixed Charge in Metal-Aluminum Oxide-Silicon Tunnel Diodes
摘要： Here, a controlled variation in the fixed charge density (NF) and thickness of aluminum oxide tunnel insulators is reported, and the impact on Schottky barrier height ΦB in metal–insulator–semiconductor (MIS) diodes is studied. Analysis of metal–aluminum oxide–silicon capacitor structures indicates a change in NF from t1 × 1012 cm?2 in as-deposited films to ?1 × 1012 cm?2 in annealed films. An analytical model and numerical device physics simulations are used to predict changes in ΦB based on these changes in NF and alumina thickness. Surprisingly, Mott–Schottky derived ΦB values did not follow the trends predicted by these electrostatic models. In fact, there seems to be no discernable effect of NF in diodes with alumina thicknesses below 2 nm, contrary to contactless measurements of the fixed charge of films of similar thickness. The ΦB trends are better explained by a dipole model. It is further shown that in as-deposited MIS diodes, the dipole is a function of alumina layer thickness, whereas in annealed MIS diodes, the dipole and ΦB were roughly constant independent of alumina thickness. These data suggest a strategy by which the ΦB of MIS tunnel contacts can be controlled and which has implication for the design of electrical contacts.
关键词： atomic layer deposition,fixed charges,silicon,barrier height,Schottky diodes
更新于2025-09-23 15:21:01
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The influence of electrode for electroluminescence devices based on all-inorganic halide perovskite CsPbBr<sub>3</sub>
摘要： Electroluminescence devices based all-inorganic halide perovskite material with the excellent luminescence performance have been studied extensively in recent years. However, the important role for the electrodes of electroluminescence devices is payed few attention by theoretical and experimental studies. Appropriate electrodes can reduce the Schottky barrier height to decrease the energy loss, and prevent the metal impurities from diffusing into the perovskite material to generate deep traps levels, which improves the luminous efficiency and lifetime of devices. In this paper, not only the interface effects between CsPbBr3 and common metal electrode (Ag, Au, Ni, Cu and Pt) are studied by first-principle calculations, but also the diffusion effects of metal electrode atom into the CsPbBr3 layer are also explored by nudged elastic band calculations. The calculated results show the metal Ag is more suitable for the cathode for CsPbBr3 electroluminescence devices, while the metal Pt is more applicable for the anode. Based on the overall consideration about the interface effects and diffusion effects of the CsPbBr3-metal electrode junctions, the essential principle provide a valuable reference how to select the suitable electrodes for other electroluminescence devices.
关键词： electroluminescence devices,diffusion effects,Schottky barrier height,CsPbBr3,all-inorganic halide perovskite,metal electrodes
更新于2025-09-23 15:19:57
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Growth of Ag(1?1?1) on Si(1?1?1) with nearly flat band and abrupt interface
摘要： Growth of Ag films of up to 30 nm thickness on Si(1 1 1) 7 × 7 at room temperature is investigated by low energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). LEED revealed the coexistence of Ag and Si spots starting with 1 monolayer (ML) of Ag deposited. The Ag lattice constant, starting with 25 ML, is slightly higher than for bulk Ag and increase linearly with Ag thickness, reaching about 4.2 nm for the thickest films. The average terrace widths detected from LEED spot profile analysis are about 30 nm for clean Si(1 1 1) 7 × 7 and about 5.5 nm for the thickest Ag(1 1 1) film, in agreement with STM observations. The intensity variation of core levels analyzed by XPS is taken into account by a model assuming the initial formation of Ag islands with linear variation of coverage vs. the amount of Ag deposited, followed by growth in a quasi layer-by-layer mode. The interface barrier is in the range of 0.4 eV, lower than all values reported previously. Ag deposited on Si(1 1 1) 7 × 7 at room temperature provides flat Ag(1 1 1) for synthesis of 2D materials, and may be used for low barrier Schottky diodes.
关键词： Scanning tunneling microscopy,Low energy electron diffraction,X-ray photoelectron spectroscopy,Ag/Si(1 1 1),Molecular beam epitaxy,Surface barrier height
更新于2025-09-23 15:19:57
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Effect of electron radiation on electrical parameters of Zn/n-Si/Au–Sb and Zn/ZnO/n-Si/Au–Sb diodes
摘要： In this study, RF-magnetron sputtered ZnO thin film as an interlayer was used to improve radiation tolerance of the Schottky diodes. The structural and optical measurements showed that the ZnO thin films have hexagonal crystal structure with preferential c-axis orientation, 20.39 nm grain sizes and 3.15 eV bandgap. The electrical parameters such as ideality factor, barrier height and series resistance of Zn/n-Si/Au–Sb and Zn/ZnO/n-Si/Au–Sb diodes were calculated before and after electron radiation at 25, 50 and 75 gray doses. Deviation values of the parameters showed that the ZnO as an interlayer caused to improved radiation tolerance of the diodes.
关键词： Zinc oxide,Barrier height,Schottky diode,Electron radiation,Heterojunction
更新于2025-09-19 17:15:36
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[IEEE TENCON 2019 - 2019 IEEE Region 10 Conference (TENCON) - Kochi, India (2019.10.17-2019.10.20)] TENCON 2019 - 2019 IEEE Region 10 Conference (TENCON) - An Alternative Approach to Voltage Dependent Reduction of Schottky Barrier Height Modeling in Two Dimensional MSM Photodetectors
摘要： Current-voltage (I-V) characteristics of a two dimensional MSM photodetector can be explained by modified thermionic emission diffusion (TED) theory. The theory assumes that Schottky barrier height (SBH) decreases linearly with bias voltage and hence voltage dependent reduction of SBH is understood in term of a series resistance (Rs) and ideality factor (n). Characterization of Rs and n can be done from dV d(lnI) vs I plot. However, in this paper we are presenting an alternative approach to understanding characteristics of voltage dependent reduction of SBH. We are proposing an exponential relationship between reduction of SBH and bias voltage to understand non ideality of Schottky junctions. By applying this relationship directly into the Richardson-Dushman equation photocurrents of different Transition-Metal Dichalcogenides(TMD) based devices can be estimated analytically. This model offers a simplistic approach for understanding non ideal behaviour of Schottky barrier height. Using this model we have calculated I-V characteristics of four different TMD based photodetectors under illumination as reported in literature. We have observed good agreement of our calculated results with experimental values. Mean absolute error in each of the cases was found to be not more than 6% in these calculations.
关键词： Perovskite,Voltage Dependent Schottky Barrier Height,Transition-Metal Dichalcogenide,Photodetector
更新于2025-09-16 10:30:52