Electrical Properties Of Films Research Articles

Effect of deposition cycle and annealing on the structural, optical, electrical, and photoluminescence properties of SnS films obtained from rapid S-SILAR technique

AbstractIn this paper, we present an optimized procedure for depositing SnS thin films using the rapid S-SILAR technique. We also analyze the effects of deposition cycles and post-deposition annealing on various film properties. XRD analysis indicates the presence of orthorhombic and cubic phases in the films. Energy dispersive X-ray analysis confirms near-optimal stoichiometry. SEM images depict the growth of closely spaced spherical granules. High optical absorption is observed in the mid-visible to NIR region, with the absorption edge shifting towards the NIR region after annealing. The bandgap values range from 1.6 eV to 1.9 eV, which is ideal for photovoltaic applications. PL spectra show three clusters of peaks corresponding to red and green emissions. Hall measurements confirm that both the as-deposited and annealed SnS films exhibit p-type conductivity, with a hole concentration on the order of 1015 cm−3.

Insight into the Role of Rb Doping for Highly Efficient Kesterite Cu2ZnSn(S,Se)4 Solar Cells.

Various copper-related defects in the absorption layer have been a key factor impeding the enhancement of the efficiency of Cu2ZnSn(S,Se)4 (CZTSSe) solar cells. Alkali metal doping is considered to be a good strategy to ameliorate this problem. In this article, Rb-doped CZTSSe (RCZTSSe) thin films were synthesized using the sol-gel technique. The results show that the Rb atom could successfully enter into the CZTSSe lattice and replace the Cu atom. According to SEM results, a moderate amount of Rb doping aided in enhancing the growth of grains in CZTSSe thin films. It was proven that the RCZTSSe thin film had the densest surface morphology and the fewest holes when the doping content of Rb was 2%. In addition, Rb doping successfully inhibited the formation of CuZn defects and correlative defect clusters and promoted the electrical properties of RCZTSSe thin films. Finally, a remarkable power conversion efficiency of 7.32% was attained by the champion RCZTSSe device with a Rb content of 2%. Compared with that of un-doped CZTSSe, the efficiency improved by over 30%. This study offers new insights into the influence of alkali metal doping on suppressing copper-related defects and also presents a viable approach for improving the efficiency of CZTSSe devices.

Effect of Sb2S3 sacrificial layer thickness on structural, optical and electrical properties of CuSbS2 films and investigation of diode parameters of CuSbS2/CdS heterojunctions

The ternary copper chalcogenides CuSbS2 (CAS) is found to have appealing optical and photovoltaic properties to be used as absorber layer in thin film solar cells. However, the difficulty to grow good quality CuSbS2 layer of micrometer thickness by chemical bath deposition method holds a big challenge. In this work, we reported the effect of incorporating Sb2S3 sacrificial layer of different thickness on structural, optical and electrical properties of CAS films. The X-ray diffraction results and Raman spectroscopic analysis confirm the formation of single-phase orthorhombic crystal structure for CuSbS2. The increase of Sb content in CAS films with the increase in deposition time of Sb2S3 layer has been reflected in the change in relative intensity ratio of characteristic Raman peaks as well as in diffraction peak profiles. The magnitude of defect states in terms of Urbach energy is decreased drastically by increasing Sb percentage in the films. A clear improvement in electrical properties of CAS films is observed with the decrease in Cu/Sb ratio. The carrier density is increased by one order of magnitude from 1016 to 1017 cm−3 and hole mobility increases from 1.14 to 4.87 cm2/Vs. The impact of Sb concentration on Scottky diode parameters of CAS/CdS heterojunction was studied by using thermionic emission model. Both the ideality factor and series resistance are decreased with the increase in Sb content. The J-V measurements reveal that the integration of Sb2S3 sacrificial layer improves the PV parameters such as fill factor, open circuit voltage, photocurrent and efficiency. The overall improvement in diode parameters can be ascribed to decrease in defect states, better film quality, absorber layer thickness and improved stoichiometry of CAS films.

Tailoring the physicochemical and electrical properties of ZnO thin films by doping with light and heavy rare-earth element via wet chemical approach

Tailoring the physicochemical and electrical properties of ZnO thin films by doping with light and heavy rare-earth element via wet chemical approach

Na+ doped CuO: A new paradigm electrode material for high performance supercapacitors

This study investigates the influence of sodium doping on the properties of cupric oxide (CuO) thin films synthesized via spray pyrolysis. Comprehensive characterization was conducted using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDAX), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), Raman spectroscopy, Hall effect measurements, and electrochemical studies. All films exhibited p-type conductivity, with an optical band gap variation from 1.53 to 1.73 eV. XRD analysis confirmed the dominance of monoclinic CuO, with minor phases of Cu2O and Cu4O3. EDAX and XPS verified the incorporation of Cu, O, and Na elements. FESEM revealed a densely packed morphology with uniform particle distribution and rough surfaces in the electrically optimized film. The Raman spectra of doped samples showed increased intensity and sharpness, attributed to Na + ion-induced polarizability enhancement. Hall effect measurements indicated a tenfold decrease in carrier concentration and a more than tenfold increase in mobility upon sodium doping. Films doped with 4 at.% sodium exhibited the lowest resistivity. Additionally, Na doping enhanced the electrochemical performance of CuO. These findings demonstrate that sodium doping significantly enhances the electrical, optical and electrochemical properties of CuO thin films, making them suitable for applications in optoelectronic devices and supercapacitors.

Investigating the electrical and thermal properties of Cu and Al-doped ZnO thick films using the screen-printing technique for thermal resistance applications

The important properties of prepared Zinc Oxide (ZnO) thick films were investigated. The electrical and thermal properties of ZnO thick films were measured and analyzed using the MATLAB simulation tool. On a glass substrate, thick films of pure ZnO as well as ZnO doped with Cu and Al materials were fabricated using the screen-printing technique. The electrical parameters were calculated using the half-bridge approach to determine the unknown resistance, change in current, and voltage. The half-bridge circuit having a 50 M Ω reference resistance with 30 V excitation voltage. The thermocouple transducer (K type) was used to measure the heating and cooling temperature between 40 °C to 370 °C. The measured maximum TCR values are 0.0095 ppm/°C for pure ZnO film, 0.0068 ppm/°C for Cu-doped ZnO film, and 0.0123 ppm/°C for Al-doped ZnO film. The maximum measured resistance values are 5.9 × 107 Ω for pure ZnO film, 5.9 × 107 Ω for Cu-doped ZnO film, and 5.9 × 107 Ω for Al-doped ZnO film. Using MATLAB simulation, it was possible to observe key factors including the activation energy, unknown resistance, IV characteristics, thermal properties, temperature coefficient resistance (TCR) and resistive linear behavior of the ZnO films.

Structural, Electronic Structure, and Electrical Properties of Pure and Vanadium-Doped CuCrO2 Thin Films

Structural, Electronic Structure, and Electrical Properties of Pure and Vanadium-Doped CuCrO2 Thin Films

Substitution of an isovalent Te-ion in SnSe thin films for tuning optoelectrical properties

In present work, SnSe1-xTex thin films with varying Te concentrations were deposited on glass substrate through thermal evaporation technique. SnSe1-xTex thin films were characterized using X-ray diffraction (XRD), atomic force microcopy (AFM), X-ray photoelectron spectroscopy (XPS), UV–Vis NIR spectroscopy and room-temperature hall measurements technique. XRD patterns revealed that all the samples had a polycrystalline orthorhombic structure. Additionally, a low level of Te impurity improved the crystalline quality of the SnSe thin films. AFM images showed a noticeable alteration in the surface structure of the SnSe thin films caused by Te doping. UV–Vis NIR spectroscopy was employed to assess the optical characteristics of SnSe1-xTex thin films, revealing a variation in the optical band gap energy (Eg) between 1.75 and 1.89 eV, attributed to Te doping. The Hall effect measurement revealed n-type conductivity, and the carrier concentration decreased as the Te dopant concentration increased, corresponding to a decrease in antisite SnSe defects. The experimental findings suggest that adding a moderate amount of Te is a beneficial method for enhancing the optical and electrical properties of SnSe films. Furthermore, the Schottky device parameters of the Ag/SnSe1-xTex/Al:ZnO structure were established by analyzing the temperature-dependent Current-Voltage (I–V-T) characteristics through the thermionic emission current transport mechanism.

MXene-CNC super performing composite films for flexible and degradable electronics

Flexible electronics have gained significant interest due to their potential applications in wearable devices, biomedical sensors, and flexible displays. This study explores the combination of MXene and cellulose nanocrystals (CNC) for the development of flexible, conductive, and degradable materials. CNC and MXene are high-performance nanomaterials with known degradability. CNC can self-assemble into highly ordered layers and act as an ideal structural companion for enabling large surface MXene-based devices with outstanding performance. Three fabrication routes are explored in this work: self-assembly, drop casting, and dip coating. The mechanical and electrical properties of the CNC-MXene composite films were assessed. Tensile testing revealed that dip-coated films in high-loadings of MXene could exhibit enhanced toughness of up to 1.9 MJ‧m−3, higher than pure MXene or CNC. The electrical conductivity of the films varied depending on MXene concentration and drying, exhibiting superior conductivity in self-assembly with higher MXene loading and rapid drying that prevents oxidation. Self-assembled MXene-CNC with a 1:3 MXene-to-CNC ratio maintained high conductivity of 2.2 × 105 S‧m−1. Zeta potential measurements indicate that CNC enhances the stability of MXene dispersion. These findings demonstrate good synergy between CNC and MXenes for applications in flexible, transparent, and environmentally degradable electronic.

Enhanced optical and electrical properties of Nb-doped TiO2 thin films synthesized by atomic layer deposition using the supercycle strategy

Herein, we report highly transparent and conductive Nb-doped TiO2 thin films successfully grown by a thermal ALD process at 300 °C using titanium tetraisopropoxide, niobium(V) ethoxide, and water. The deposition was carried out by employing a supercycle approach, alternating cycles of Ti precursor followed by a monocycle of Nb precursor, thereby enabling precise control over the Nb dopant concentration. We demonstrate the crucial impact of the dopant concentration and annealing conditions played on the thickness, structure, morphology, composition, and optical and electrical properties of the resulting films. The incorporation of niobium dopants led to significant improvements in the film's characteristics. The Nb-doped TiO2 films exhibited an enhanced optical transmission efficiency up to 15 %, along with a remarkable reduction in resistivity by four orders of magnitude, reaching 10−3 Ω.cm, compared to undoped TiO2 films. These high performances establish Nb-doped TiO2 thin films as promising TCOs with wide-ranging applications in fields that require efficient current collection or injection in conjunction with optical radiation transmission.

Critical factors for enhancing electrical performance in LaGdO3 capacitor

This study investigates the characteristics of metal/LaGdO3/Si capacitors using LaGdO3 as the dielectric material. LaGdO3 thin films were deposited using radio-frequency magnetron sputtering, and the effects of different process parameters, such as annealing temperature, electrode materials, and oxygen ratio, on the capacitance characteristics were investigated. Results showed that the presence of oxygen vacancies affects the dielectric constant, flat-band voltage, and breakdown field of LaGdO3 films. The optimal annealing temperature for the LaGdO3/Si stack was identified to be 600 °C, resulting in a dielectric constant of 13.9 and a flat-band voltage shift of 0.1 V. Introducing 10 % O2 during deposition effectively repaired oxygen vacancies in the film, while excessively high oxygen proportions resulted in a lower dielectric constant and a higher flat-band voltage shift. Moreover, the electrode material was found to affect the capacitance characteristics. The dielectric constants for Al/LaGdO3/Si, Ti/LaGdO3/Si, and Pt/Ti/LaGdO3/Si capacitors were 10.0, 16.3, and 17.3, respectively. The flat-band voltage shifts were −0.7, −0.42, and −0.03 V, with hysteresis voltages of 345, 117, and 32 mV, respectively. The Pt/Ti/LaGdO3/Si device exhibited the lowest oxide defect density, indicating superior interface quality and potentially enhanced device performance. In addition, the band diagrams for metal/LaGdO3/Si were constructed. This study demonstrates that oxygen vacancies and electrode materials are crucial factors influencing the capacitance characteristics of LaGdO3 films. The electrical properties of LaGdO3 films can be effectively improved by controlling process parameters, enhancing their potential for applications in capacitors and other electronic devices.

Novel deuterated cyclopentadienyl zirconium/hafnium precursors for atomic layer deposition of high-performance ZrO2/HfO2 thin films

The need to improve the electrical properties of ZrO2 and HfO2 thin films deposited by atomic layer deposition (ALD), which is widely used in the field of microelectronics, is growing. Attempts to improve precursor stability unavoidably lead to reduced reactivity and diminished utility. Therefore, we synthesized and developed two new ALD precursors by introducing deuterium, which simultaneously exhibit enhanced thermal stability and enhanced reactivity as a result of the introduction of deuterium. For the substitution of deuterium for hydrogen in the precursors responsible for the enhanced thermal stability, we experimentally and theoretically demonstrated that thermal stability and reactivity can be simultaneously enhanced by reducing the bonding dissociation energy of ligands that have not undergone deuterium substitution. This observation led to the development of ZrO2 and HfO2 ALD processes that result in no impurities within the thin films and minimal substrate damage even at a very high deposition temperature of 400 °C. In particular, the improvement in crystallinity through ultra-high-temperature ALD deposition resulted in excellent electrical properties in a metal–insulator–metal capacitor in which the film was incorporated; the capacitor demonstrated a dielectric constant of 37.9 and leakage current of 3.52 × 10−9 A cm−2, without the need for a subsequent annealing process.

Tailoring the structural, optical, hydrophobicity and electrical properties of ZnO thin films by copper doping for self-clean optoelectronic application

Optoelectronic devices such as solar panels, cameras, screens, and sensors frequently suffer reduced performance due to dust accumulation. Incorporating self-cleaning features not only sustains their efficiency but also minimizes maintenance expenses, especially for large or challenging-to-access setups. In this study, copper doped-zinc oxide (CZO) thin films with varying copper (Cu) concentrations were created using the reactive co-sputtering process. These films underwent a comprehensive analysis, including X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy to examine their structure, morphology, and elemental composition. Optical properties were investigated through UV–Vis spectroscopy, while hydrophobicity and electrical characteristics were assessed with contact angle and I–V measurements. Spectroscopic ellipsometry was employed to analyse surface attributes. The results confirmed that as Cu concentrations increased, the crystallite and grain size of ZnO in the films also increased. A red shift in the band gap was observed in UV–Vis spectroscopy, and Cu doping effectively reduced the electrical resistivity of the ZnO thin film. The CZO thin film, with a 60 nm thickness, low roughness (1.49 nm), high optical transmittance (around 80.20 %), a wide band gap (3.22 eV), a substantial contact angle (113°), and low electrical resistivity (5.9 × 105 Ω cm), holds great promise for use in transparent, conductive, and self-cleaning optoelectronic devices.

A Highly Responsive Graphene Oxide Humidity Sensor Based on PVA Nanofibers.

Graphene oxide (GO) humidity sensors based on poly(vinyl alcohol) (PVA) nanofibers have been proposed. The PVA nanofiber layers of different densities were obtained by adjusting the electrospinning time. Then, GO films were deposited on PVA nanofibers by a spin-coating method. The electrical properties of GO films are improved due to the increased distribution of PVA nanofibers in the GO films. The humidity sensors exhibit good sensitivity under a high relative humidity range of 40-80%. The response of sensors has reached 98.44% at a humidity level of 80% RH. The GO/PVA sensors have good stability at various humidity levels for 1 week. Furthermore, the GO/PVA sensors were used for respiration monitoring under different statuses. These sensors have good application prospects in the respiratory detection and analysis of diseases.

Improvement of electrical and optoelectronic properties of ZnO thin films by plasma nitridation treatment

Understanding and controlling the effects of trap sites in ZnO semiconductors are crucial for optimizing device performance and enabling various technological applications. To passivate the trap sites, the N atoms are incorporated into polycrystalline ZnO thin films via a plasma nitridation (PN) process using NH3 gas. The results show that the contact resistivity, sheet resistance, and transfer length of the ZnO photodetector are improved after the PN treatment. The photo-to-dark current ratio (PDCR) and responsivity values increase from 42.52 to 103.19 and from 344.36 A/W to 5727.63 A/W, respectively, after the PN treatment. This improvement in photodetector properties is attributed to the introduced N atoms, which effectively reduce the trap sites in the ZnO thin film. This PN treatment technology has the potential to improve device performance in both electronic and optoelectronic applications.

Electrical, Optical and Thermal Properties of Ge-Si-Sn-O Thin Films.

This work evaluates the electrical, optical and thermal properties of Sn-doped GexSi1-xOy thin films for use as microbolometer sensing materials. The films were prepared using a combination of a radio frequency (RF) magnetron and direct current (DC) sputtering using a Kurt J Leskar Proline PVD-75 series sputtering machine. Thin films were deposited in an O2+Ar environment at a chamber pressure of 4 mTorr. The thicknesses of the thin films were varied between 300 nm-1.2 µm by varying the deposition time. The morphology and microstructure of thin films were investigated by atomic force microscope (AFM) imaging and X-ray diffraction (XRD), while the atomic composition was determined using the energy dispersive spectroscopy (EDS) function of a scanning electron microscope. The thin film with an atomic composition of Ge0.45Si0.05Sn0.15O0.35 was found to be amorphous. We used the Arrhenius relationship to determine the activation energy as well as temperature coefficient of resistance of the thin films, which were found to be 0.2529 eV and -3.26%/K, respectively. The noise voltage power spectral density (PSD) of the film was analyzed using a Primarius-9812DX noise analyzer using frequencies ranging from 2 Hz to 10 kHz. The noise voltage PSD of the film was found to be 1.76 × 10-11 V2/Hz and 2.78 × 10-14 V2/Hz at 2 Hz and 1KHz frequencies, respectively. The optical constants were determined using the ellipsometry reflection data of samples using an RC2 and infrared (IR) VASE Mark-II ellipsometer from J A Woollam. Absorption, transmission and reflection data for a wavelength range of 900 nm-5000 nm were also determined. We also determined the optical constant values such as the real and imaginary parts of refractive index (n and k, respectively) and real and imaginary part of permittivity (ε1 and ε2, respectively) for wavelength ranges between 193 nm to 35 µm. An optical band gap of 1.03 eV was determined from absorption data and using Tauc's equation. In addition, the thermal conductivity of the film was analyzed using a Linseis thin film analyzer employing the 3ω method. The thermal conductivity of a 780 nm thick film was found to be 0.38 Wm-1K-1 at 300 K. From the data, the Ge-Si-Sn-O alloy was found to be a promising material for use as a sensing material for microbolometers.

Doped SnO2 thin films fabricated at low temperature by atomic layer deposition with a precise incorporation of niobium atoms

Nb-doped SnO2 (NTO) thin films were synthesized by atomic layer deposition technique at low temperature (100 °C). For an efficient incorporation of the Nb atoms, i.e. fine control of their amount and distribution, various supercycle ratios and precursor pulse sequences were explored. The thin film growth process studied by in-situ QCM revealed that the Nb incorporation is highly impacted by the surface nature as well as the amount of species available at the surface. This was confirmed by the actual concentration of the Nb atom incorporated inside the thin film as determined by XPS. Highly transparent thin films which transmit more than 95% of the AM1.5 global solar irradiance over a wide spectral range (300–1000 nm) were obtained. In addition, the Nb atoms influenced the optical band gap, conduction band, and valence band levels. While SnO2 thin film were too resistive, films tuned to conductive nature upon Nb incorporation with controlled concentration. Optimal incorporation level was found to be ⩽1 at.% of Nb, and carrier concentration reached up 2.5 × 1018 cm−3 for the as-deposited thin films. As a result, the high optical transparency accompanied with tuned electrical property of NTO thin films fabricated by ALD at low temperature paves the way for their integration into temperature-sensitive, nanostructured optoelectrical devices.

Influence of multi-doping (Zn and Sn) on the optical, and electrical properties of spray-deposited CdO thin films

This investigation has been focused on the spray-deposited pure cadmium oxide (CdO) thin films and also doped with zinc (Zn) and tin (Sn), as a transparent conducting oxide for optoelectronic applications. By varying the concentration of Sn (0–2%) into CdO, the microstructural, morphological, and optoelectronic properties were investigated. XRD spectra confirmed the polycrystalline cubic structure of the pure, doped, and co-doped CdO films. SEM investigation reveals the crack-free homogeneous cauliflowers-like morphology of the fabricated thin films. The existence of elemental compositions such as Cd, Zn, Sn, and O in the prepared films was confirmed by EDS analysis. All of the doped and co-doped CdO films showed good transparency in the visible range. Moreover, a slight increment has been found in the optical band gap from 2.43 eV to 2.50 eV with increasing Sn concentration, which can be explained by the Burstein-Moss phenomena. A decrement of Urbach energy was noted for an increased concentration of Sn. Besides, Zn and Sn (1 %) co-doped films exhibited the lowest electrical resistivity value 4.09×10−4 Ω-cm among other doped compositions. However, the addition of Zn and Sn into CdO thin films enhanced the optoelectronic properties.

Enhanced Thermoelectric Performance in Flexible Sulfur-Alloyed Ag2Se Thin Films.

Flexible thermoelectric generators can directly convert thermal energy harvested from the human body into electricity. The Ag2Se flexible film, a promising material for wearable thermoelectric generators, normally demonstrates an inferior electrical transport property due to its weakened in-plane mobility. In this study, the in-plane electrical transport properties of flexible Ag2Se films were optimized by alloying with additional sulfur. This optimization is achieved by leveraging the differences in elemental electronegativity and the preferred orientation of the Ag2Se films. The sulfur-alloyed Ag2Se thin film, with a nominal ratio of 3 atom %, can reach a maximum mobility of 1150 cm-2 V-1 s-1 at 300 K. So, the optimized room-temperature power factor increases to 1935 μW m-1 K-2. Furthermore, the Ag2Se film alloyed with 3 atom % sulfur exhibits excellent flexibility even after 1000 bending cycles with a radius of 5 mm, characterized by a relative resistance increment of less than 3%. In addition, the corresponding π-type flexible thermoelectric generator possesses a maximum power density of 51 W m-2 at a temperature difference of 50 K.

Conductive NR/PMMA-RAFT-CNT-rGO composites and their morphological, mechanical, and electrical properties

This study reports the synthesis of poly(methyl methacrylate) (PMMA)-carbon nanotube (CNT)-reduced graphene oxide (rGO) emulsions via reversible addition-fragmentation chain-transfer (RAFT)-mediated surfactant-free emulsion polymerization using a hydrophilic chain transfer agent. The rGO was prepared by the modified Hummers method and reduced with L-ascorbic acid. The effects of the CNT:rGO ratios and CNT and rGO contents on the conversion and stability of emulsion were investigated. Increasing the CNT and rGO contents from 1 to 4 wt% decreased the monomer conversion, while all the samples remained as colloidal dispersions. The morphology of PMMA-CNT-rGO composites showed the incorporated arrangement of a linear CNT portion connected with the rGO sheet dependent on the CNT:rGO ratio. Various PMMA-CNT-rGO filled natural rubber (NR) cast films were prepared. The NR/PMMA-CNT-rGO composite film with a 1 wt% filler loading at a CNT:rGO ratio of 1:1 presented a quite high modulus value (3.08 MPa) and sufficient intrinsic electrical conductivity (1.36 S/m) due to its strong filler-matrix interaction. Thus, the PMMA-RAFT-CNT-rGO composites at a very low filler content can be used as an effective reinforcement to enhance the mechanical and electrical properties of NR films with a high compatibility between the fillers and NR matrix.