Electrical Properties Of Films Research Articles

Carbon-doped ZnO thin films: A transparent conductive oxide for application in solar-blind photodetectors

Transparent conductive oxide (TCO) films are crucial in optoelectronic devices, such as photodetectors, due to their unique blend of transparency and electrical conductivity. ZnO is a top choice for TCOs owing to its excellent properties, non-toxicity, and cost-effectiveness. In this work, we explore the potential of carbon doping to enhance the electrical properties of ZnO films for transparent conductive applications. Our findings reveal that C-doped ZnO (ZnO:C) films retain the pristine high quality and surface morphology despite an increase in defects with higher C doping. Notably, C doping does not compromise the visible light transmittance of ZnO films, while inducing a gradual increase in optical bandgap, indicative of the typical Burstein–Moss effect. As carbon doping increases, the ZnO:C films exhibit improved carrier concentration, lower resistivity, and sustained high mobility, achieving optimal performance with an electron concentration of 3.73 × 1019 cm−3, resistivity of 3.69 × 10−3 Ω cm, and mobility of 46.08 cm2 V−1 s−1. Finally, we utilized ZnO:C films as a transparent electrode material in ε-Ga2O3-based photodetector, achieving the development of transparent device and attaining high-performance solar-blind detection capabilities. This work provides a strategy for developing a transparent conductive oxide, with ZnO:C emerging as a promising rival to IIIA-doped ZnO for optoelectronic applications.

Preparation of Sn-Doped Ga2O3 Thin Films and MSM Ultraviolet Detectors Using Magnetron Co-Sputtering.

Sn-doped Ga2O3 thin films and metal-semiconductor-metal (MSM) ultraviolet detectors were prepared using the co-sputtering method to enhance their photoelectric performance. The results revealed that Sn doping can effectively change the optical and electrical properties of thin films, greatly improving the photoelectric responsiveness of the devices. Through microstructure testing results, all of the thin film structures were determined to be monoclinic beta phase gallium oxide. At a DC power of 30 W, the thickness of the Sn-doped thin film was 430 nm, the surface roughness of the thin film was 4.94 nm, and the carrier concentration, resistivity, and mobility reached 9.72 × 1018 cm-3, 1.60 × 10-4 Ω·cm, and 45.05 cm3/Vs, respectively. The optical results show that Sn doping clearly decreases the transmission of thin films and that the bandgap can decrease to 3.91 eV. Under 30 W DC power, the photo dark current ratio of the detector can reach 101, time responses of tr = 31 s and tf = 22.83 s were obtained, and the spectral responsivity reached 19.25 A/W.

Enhanced Deposition Selectivity of High-k Dielectrics by Vapor Dosing and Selective Removal of Phosphonic Acid Inhibitors.

Area-selective atomic layer deposition (AS-ALD), which provides a bottom-up nanofabrication method with atomic-scale precision, has attracted a great deal of attention as a means to alleviate the problems associated with conventional top-down patterning. In this study, we report a methodology for achieving selective deposition of high-k dielectrics by surface modification through vapor-phase functionalization of octadecylphosphonic acid (ODPA) inhibitor molecules accompanied by post-surface treatment. A comparative evaluation of deposition selectivity of ZrO2 thin films deposited with the O2 and O3 reactants was performed on SiO2, TiN, and W substrates, and we confirmed that high enough deposition selectivity over 10 nm can be achieved even after 200 cycles of ALD with the O2 reactant. Subsequently, the electrical properties of ZrO2 films deposited with O2 and O3 reactants were investigated with and without post-deposition treatment. We successfully demonstrated that high-quality ZrO2 thin films with high dielectric constants and stable antiferroelectric properties can be produced by subjecting the films to ozone, which can eliminate carbon impurities within the films. We believe that this work provides a new strategy to achieve highly selective deposition for AS-ALD of dielectric on dielectric (DoD) applications toward upcoming bottom-up nanofabrication.

The electrical properties of nitrogen-doped vanadium dioxide thin films grown by magnetron sputtering

Abstract Vanadium dioxide (VO2) undergoes a reversible semiconductor-metal phase transition near 68°C, and the optical and electrical properties could be changed in femtoseconds. These unique characteristics meet the electro-optic switch applications. In this work, to improve the intrinsic characteristics of VO2, a series of nitrogen-doped vanadium dioxide thin films were prepared by reactive magnetron sputtering. Moreover, the effects of different nitrogen flow rates on the microstructure, surface morphology, electrical properties and phase transition properties of the samples were investigated. The samples are characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), four-point probe system, and Hall effect et al. Sheet resistance variation at room temperature and high temperatures indicates remarkable semiconductor-metal transition characteristics. According to results of Hall effect measurement, when nitrogen flow rate is less than 1 sccm, the samples exhibits p-type semiconductor characteristics. However, while nitrogen flow rate reaches 1 sccm, n-type semiconductor characteristics appear. What’s more, Carrier mobility reaches a maximum at a nitrogen to oxygen flow ratio of 0.3. The results reveal that the samples have a great potential on electro-optic switching applications.

Study of the effects of heating on the physical, optical, and electrical properties of NiO thin films synthesized using a low-cost sol-gel method

Developments in low-cost techniques for growing high-quality nickel oxide thin films (NiOTFs) are critical enablers for the fabrication of NiO-based devices, particularly solar cells, light-emitting diodes, lasers, and many other applications. In this study, it has been demonstrated that the optical, electrical, and structural characteristics of NiOTFs coated on glass substrate employing a low-cost solution method are strongly influenced by post-thermal annealing treatments in ambient air. A comprehensive study was carried out on the characteristics of the deposited NiOTFs. X-ray diffraction (XRD) measurements indicate the enhancement of the crystal quality of films after annealing. There is a noticeable change and improvement in coated NiOTFs with heat treatment at 300 and 600 ℃ due to clear shifts in density. During the heating temperature increment, the energy of the band gap was shifted from 3.63 to 3.44 eV, and the electrical resistance of the NiOTFs varied from 1020 to 700 Ω-cm. Furthermore, the results indicate that the low-cost sol-gel (SG) deposition technique has a greater potential for producing high-quality p-type NiOTFs with minimal defects for electronic device applications.

Degradation of MoOx Thin‐Films Properties in Excessive Oxygen Environments and Its Influence on Dopant‐Free Silicon Solar Cells

Transition metal oxides such as molybdenum oxide (MoOx) demonstrate significant potential as efficient hole‐selective passivating contacts in silicon heterojunction solar cells. Achieving efficient hole collection necessitates precise control over the optical and electrical properties of MoOx films. In this study, the effects of oxygen flow rate () on the growth, optical properties, and electrical properties of thermally evaporated MoOx films are investigated. In the Kelvin probe force microscopy results, it is indicated that MoOx thin‐film deposition followed an island‐to‐layer growth model. X‐ray photoelectron spectroscopy shows that MoOx films exhibit stoichiometric composition with fully oxidized Mo6+ ions, without additional oxygen. Notably, the O 1s orbital peak shifts toward higher binding energy with increased , indicating defect introduction. Consequently, the work function of MoOx films decreases from 5.93 to 5.51 eV as increases from 0 to 8 sccm. The maximum optical bandgap of the MoOx films exceeds 3.60 eV. As a proof of concept, 's impact on MoOx as a front buffer layer for dopant‐free silicon solar cells is analyzed. An efficiency of 20.8% was achieved for dopant‐free silicon solar cells after optimized MoOx film deposition, with an open‐circuit voltage of 713.7 mV, short‐circuit current density of 39.1 mA cm−2, and fill factor of 74.6%.

Effect of the argon flow rate and substrate temperature on the structural, morphological, optical and electrical properties of SbxTey thin films grown by radio-frequency sputtering

Sb2Te3 is a promising candidate for applications in thermoelectric thin film devices, thin film solar cells, and electronic memory devices. This study involved the preparation of SbxTey thin films using radio-frequency magnetron sputtering. By adjusting the argon flow rate and substrate temperature while using a stoichiometric Sb2Te3 sputtering target, different compositions of Sb-Te were achieved. The results revealed that an argon flow rate of 2.5 sccm with a growth temperature of 400 °C led to the formation of the Sb2Te3 compound and suppressed Te aggregates. This elimination of Te as a secondary phase resulted in a high hole density of 2.88×1020 cm−3, a low resistivity of 5.15×10−3 Ω∙cm, and a low bandgap of 0.37 eV. These characteristics make the Sb2Te3 thin films suitable as buffer layers in CdTe-based solar cells and thermoelectric devices.

Influence of Reduced Graphene Oxide and Carbon Nanotubes on the Structural, Electrical, and Photoluminescent Properties of Chitosan Films.

Chitosan is a biopolymer with unique properties that have attracted considerable attention in various scientific fields in recent decades. Although chitosan is known for its poor electrical and mechanical properties, there is interest in producing chitosan-based materials reinforced with carbon-based materials to impart exceptional properties such as high electrical conductivity and high Young's modulus. This study describes the synergistic effect of carbon-based materials, such as reduced graphene oxide and carbon nanotubes, in improving the electrical, optical, and mechanical properties of chitosan-based films. Our findings demonstrate that the incorporation of reduced graphene oxide influences the crystallinity of chitosan, which considerably impacts the mechanical properties of the films. However, the incorporation of a reduced graphene oxide-carbon nanotube complex not only significantly improves the mechanical properties but also significantly improves the optical and electrical properties, as was demonstrated from the photoluminescence studies and resistivity measurements employing the four-probe technique. This is a promising prospect for the synthesis of new materials, such as biopolymer films, with potential applications in optical, electrical, and biomedical bioengineering applications.

Enhancement of structural, optical, electrical, optoelectronic and thermoelectric properties of ZnO thin film via Ni doping and Ni-B co-doping

In this study, the effects of nickel (Ni) and boron (B) elements on the structural, optical, electrical, optoelectronic, and thermoelectric properties of zinc oxide (ZnO) material were investigated. Therefore, undoped ZnO, 3% Ni-doped ZnO (Zn0.97Ni0.03O), and 3% Ni-1% B co-doped ZnO (Zn0.96Ni0.03B0.01O) solutions were prepared by the sol gel method. The produced solutions were coated on glass and p-type Si substrates via dip coating and spraying methods in the form of thin films. We produce pure and n-type semiconductors in the form of nanodots which have wurtzite ZnO polycrystalline structure for all samples. Ni and B co-doped sample is morphologically, electrically and optically enhanced the ZnO material with 3.08 eV band gap, homogenous surface and the highest electrical conductivity. In addition, the best material among the three samples that can be used as a visible light-sensitive sensor is Zn0.96Ni0.03B0.01O under feedback voltage. Technologically, this material can be turned into a photodiode device in the form of Au/Zn0.96Ni0.03B0.01O/p-Si. While the obtained ideality factor of ZnO from the forward bias region decreases from 5.7 to 3.4, its barrier height increases from 0.636 eV to 0.667 eV and serial resistance of contact decreases from 121.6 × 103 Ω to 5.6 × 103 Ω with Ni and B co-doping. Ni doping thin film improves the photovoltaic, and thermoelectric properties of ZnO. Ni-doped ZnO sample can be studied in form of the thin films as a thermoelectric material due to its ZT value is nearly 1.73 × 10–4 at 650 K. Its thermoelectric performance is 13 times better than the that of pure ZnO for the same temperature values. The efficiency of Ni-doped ZnO sample as solar cell increases 10 times compared to pure ZnO. In addition to the production of materials with improved energy efficiency, economical products suitable for use in large areas have been obtained in this study.

Physical, optical and electrical properties of polyvinyl alcohol-graphene oxide nanocomposite films

Physical, optical and electrical properties of polyvinyl alcohol-graphene oxide nanocomposite films

Comprehensive characterization of structural, optical and electrical properties of CdS thin films annealed in air and vacuum

Comprehensive characterization of structural, optical and electrical properties of CdS thin films annealed in air and vacuum

Composite polymer films with semiconductor nanocrystals for organic electronics and optoelectronics

Organic materials and, in particular, polymer films enhanced with certain nanocrystals have a potential for wide application in electronics and optoelectronics due to their organic flexibility, lightweight, simple integration, affordable manufacturing cost, and low environmental impact of their production. The purpose of this research is to investigate the electrical properties of polymer-based composite films containing Cd1–xCuxS nanocrystals in order to determine their prospects for use as conductive layers in organic electronics and optoelectronics. The paper contains a detailed description of the synthesis method of hybrid nanocomposite films based on peroxide reactive copolymer (PRC) with Cd1–xCuxS nanocrystals. The defect structure of the films is studied by analyzing the photoluminescence spectra. Current-voltage characteristics of the films with different Cd and Cu contents in the Cd1–xCuxS nanocrystals embedded into the polymer matrix, deposited on glass substrates are measured in the dark and under light illumination. The film conductivity is found to increase with the Cu content in the Cd1–xCuxS nanocrystals. The carrier transport corresponds to the Ohm law at low voltages and the space charge limited current (SCLC) or Poole–Frenkel mechanisms at higher ones. The conductivity of the polymer-based hybrid nanocomposite films has a weak dependence on the intensity of light illumination. The explanation of the obtained experimental results is proposed.

Deep Eutectic Solvent-Based Polymer Electrolyte Films for an Electrochemical Double Layer Cell

Polymer electrolyte films based on DES were prepared with the solution cast technique. DES(ChCl-glycerol) was prepared with two different glycerols: one purchased from the industry and the other fabricated in the lab from waste vegetable oil. Two polymer electrolyte films were prepared with two different DES (industrial and from oil-based glycerol) were named D1 and D2, respectively. Fabricated polymer film (D1) with DES (prepared with industrial glycerol) shows excellent physical and thermochemical properties. The molecular and structural characteristics of the film were studied via FTIR and XRD. The surface morphology, thermal and electric properties of film were studied with SEM, TGA, and impedance spectroscopy techniques, respectively. The obtained films were flexible, strong, and transparent. Its properties are ascribed to a strong coherent hydrogen bond network with the matrix of the polymer. Polymer electrolyte film D1 exhibited good ionic conductivity of 1.25×10-3 Scm-1. The prepared polymer film was applied as solid electrolytes in symmetric solid-state supercapacitors. The fabricated EDLC cell exhibits specific capacitance of at voltage with scan rate. Moreover, the prepared electrolyte is biocompatible, environment safe and cost-effective that offers a new path for adaptable electronic devices. Keywords: Green electrolytes, Supercapacitor, Deep eutectic solvent, Hydrogen bond network, Choline chloride-glycerol.

Tuning the Optical and Electrical Properties of ALD-Grown ZnO Films by Germanium Doping.

In this work, we report on the fabrication of ZnO thin films doped with Ge via the ALD method. With an optimized amount of Ge doping, there was an improvement in the conductivity of the films owing to an increase in the carrier concentration. The optical properties of the films doped with Ge show improved transmittance and reduced reflectance, making them more attractive for opto-electronic applications. The band gap of the films exhibits a blue shift with Ge doping due to the Burstein-Moss effect. The variations in the band gap and the work function of ZnO depend strongly on the carrier density of the films. From the surface studies carried out using XPS, we could confirm that Ge replaces some of the Zn in the wurtzite structure. In the films containing Ge, the concentration of oxygen vacancies is also high, which is somehow related to the poor electrical properties of the films at higher Ge concentrations.

Electrical and structural properties of BiFeO3 thin films with four distinct buffer layers: La2O3, Pr2O3, Sm2O3, and Tm2O3

In this study, BiFeO3 thin films were fabricated using a spin-coating technique on SrRuO3/n+-Si substrates, employing four different RE2O3 (La2O3, Pr2O3, Sm2O3, and Tm2O3) buffer layers. The investigation focused on assessing the structural and ferroelectric characteristics of these films. X-ray diffraction analysis revealed a (110) preferred orientation with a perovskite-rhombohedral structure in films with RE2O3 buffer layers. Atomic force microscopy analysis indicated smooth surfaces for these layers. Secondary ion mass spectrometry demonstrated high levels of Bi ions in films with RE2O3 buffer layers, while X-ray photoelectron spectroscopy revealed a low Fe2+/Fe3+ ratio in these layers. Notably, the film with a Sm2O3 buffer layer showed a lower leakage current (2.05 × 10−6 A/cm2) and a higher remnant polarization (43.65 μC/cm2). This improvement is attributed to Sm3+ ions fostering (110) orientation, reducing surface roughness, increasing Fe3+ content, thereby minimizing oxygen vacancies, and suppressing Fe3+ to Fe2+ valence fluctuation.

Facile synthesis and characterization of PbS thin films doped with various aluminum concentrations for photovoltaic applications

In this study, aluminum doped lead sulfide (PbS:Al) thin films were deposited on soda lime glass substrates using chemical bath deposition (CBD) technique. The structural, morphological, optical and electrical properties of as-deposited PbS thin films were studied as a function of Al concentration (0, 2, 4, 6, 8 at. %). The deposited films can be analyzed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), x-ray diffraction (XRD), UV-Vis-NIR spectroscopy and Hall measurement. From SEM, it was evident that the thickness of the films decreased from 750 nm (0 at. %) to 280 nm (8 at. %) with increased Al concentration. XRD analysis revealed that the prepared films exhibited face centered cubic structure without any other binary phases. The average crystallite size of the films decreased from 33.71 to 20.45 nm. The direct optical band gap values were increased from 0.90 to 1.29 eV. The optical parameters such as refractive index (n), extinction coefficient (k), real (ɛ 1) and imaginary (ɛ 2) parts of the dielectric constant were 1.51–2.04, 0.0035–0.0075, 2.50–6.20 and 0.005–0.16 respectively. The absorption coefficient (α) of all the deposited films was in the range of ≈105 cm−1. The electrical resistivity of the deposited films was found in the range of 102–103 Ω·cm. The overall analysis indicate that the deposited PbS:Al thin film shows promise as an absorbing layer for heterojunction solar cell devices.

Changes in the Crystal Lattice Parameters of Bismuth Films on Substrates with Different Thermal Expansion

AbstractDue to the sensitivity of the electronic structure of semi‐metals to small distortions of the crystal lattice, the study of the electrical and galvanomagnetic properties of bismuth films requires taking into account the deformation that occurs in the film‐substrate system due to the difference in the thermal expansion of the film and substrate materials. The magnitude of these deformations plays an important role in analyzing the temperature dependencies of the transport properties of charge carriers. The paper presents an experimental study of the magnitude of deformation of bismuth films on various substrates at 300 and 77 K using X‐ray diffraction. Changes in the lattice constant of crystallites, the trigonal axis of which is perpendicular to the film plane, depending on the substrate material, are obtained. A comparison between the assessment of the deformation of these crystallites in the film plane based on Hooke's law and the difference in the coefficients thermal expansion of the film and substrate materials is made.

Enhancement of optical and electrical properties of tin oxide thin films through Zr + Ag doping for photocatalytic and photovoltaic applications

Abstract In present investigation, Pure Tin (Sn), Zirconia (Zr) and Silver (Ag) doped Sn thin films are prepared by jet nebuliser spray technique and utilised for possible photovoltaic application. A simple soft chemical technique used to create Zr and Ag doped SnO2 nanocrystalline nanoparticles. As shown by the results of the XRD analysis, the nanoparticles found a tetragonal structure with P42/mnm symmetry, in accordance with the appearance of highly crystalline SnO2. The optical properties were performed, and their bandgap energies were found to be 2.8, 3.1 and 3.2 eV, respectively. Particles of prepared SnO2 were analysed using FT-IR and XRD spectroscopy, which confirmed the presence of Zr and Ag. The photocatalytic performance of Sn–Zr–Ag NPs was examined by degradation of cationic Safranin dye under sunlight radiations with an interval of 15 min up to 90 min. UV–Vis spectrum analysis and a pseudo-first-order kinetics model were used to study nano catalytic dye degradation. High photocatalytic activities were observed after Zr and Ag doping, which may be enhanced further by adding H2O2. The surface characteristics of the prepared thin films are evaluated by AFM analysis. The electrochemical behaviour and photovoltaic properties are evaluated by EIS and IV characteristic studies.

The electrical transport property and gas detection behaviour of polyvinyl alcohol and γ-Fe2O3 nanocomposite film

This paper presents the electrical and gas detection behaviour of polyvinyl alcohol (PVA)/γ-Fe2O3 nanocomposite films. The physical characterization includes X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and UV–Visible spectroscopy. The analysis of both the dc resistivity and ac conductivity using Correlated Barrier Hoping (CBH) conduction process shows that the conductivity enhances with the decreasing of activation energy in case of the PVA/γ-Fe2O3 nanocomposite film which is the indication of interfacial defect states. The current voltage study at various temperatures follows the thermoionic emission model of Schottky Barrier diode. Moreover, the dielectric constant enhances for PVA/γ-Fe2O3 nanocomposite film, which indicates homogeneous distribution of γ-Fe2O3 nanoparticles within PVA matrix and the aggregation of trapped charges found in interface develops an interfacial polarization. As a result, the gas adsorption capacity of the nanocomposite film increases which improves the signal-to-noise ratio, leading to higher gas detection sensitivity.

Low-thermal-budget electrically active thick polysilicon for CMOS-First MEMS-last integration

Low-thermal-budget, electrically active, and thick polysilicon films are necessary for building a microelectromechanical system (MEMS) on top of a complementary metal oxide semiconductor (CMOS). However, the formation of these polysilicon films is a challenge in this field. Herein, for the first time, the development of in situ phosphorus-doped silicon films deposited under ultrahigh-vacuum conditions (~10−9 Torr) using electron-beam evaporation (UHVEE) is reported. This process results in electrically active, fully crystallized, low-stress, smooth, and thick polysilicon films with low thermal budgets. The crystallographic, mechanical, and electrical properties of phosphorus-doped UHVEE polysilicon films are studied. These films are compared with intrinsic and boron-doped UHVEE silicon films. Raman spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM) are used for crystallographic and surface morphological investigations. Wafer curvature, cantilever deflection profile and resonance frequency measurements are employed to study the mechanical properties of the specimens. Moreover, resistivity measurements are conducted to investigate the electrical properties of the films. Highly vertical, high-aspect-ratio micromachining of UHVEE polysilicon has been developed. A comb-drive structure is designed, simulated, fabricated, and characterized as an actuator and inertial sensor comprising 20-μm-thick in situ phosphorus-doped UHVEE films at a temperature less than 500 °C. The results demonstrate for the first time that UHVEE polysilicon uniquely allows the realization of mechanically and electrically functional MEMS devices with low thermal budgets.