Electrical Properties Of Films Research Articles

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.

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.

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.

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.

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.

Atomic and electronic structures of domain boundaries in LaTiO3 thin films

Domain boundaries in perovskite oxides often exhibit abundant physical properties and phenomena. Here, epitaxial LaTiO3 thin films on (100) SrTiO3 substrates are prepared by pulsed-laser deposition. X-ray diffraction and transmission electron microscopy investigations reveal that the epitaxial LaTiO3 thin films have good crystallinity but a high density of domain boundaries. Atomic-scale scanning transmission electron microscopy observations reveal that two types of domain boundaries are formed in the LaTiO3 thin films. The type I domain boundaries are formed on the {100} crystal planes, while the type II domain boundaries on the {110} crystal planes. Electron energy-loss spectroscopy analyses suggest that the valence states of Ti ions at the type I domain boundaries are +3, while those at the type II domain boundaries are +4. First-principles calculations reveal that the bandgap decreases at both domain boundaries compared to the bulk. The carrier concentration at the type I domain boundaries is significantly higher than that of the bulk, while the carrier concentration at the type II domain boundaries is lower. These findings suggest that domain boundaries play an important role in tailoring the electrical properties of the LaTiO3 thin films, thereby promoting the potential applications and property modulation of related materials and devices.

Studies of electrical resistivity and magnetic properties of CuFe and CuNiFe films prepared by magnetron sputtering

The Cu-Fe binary alloys exhibit severe elemental segregation, resulting in an inhomogeneous microstructure, which leads to differences in microregion magnetic properties, thus affecting their application. Employing magnetron sputtering to produce films is advantageous for achieving a consistent dispersion of Fe within the Cu matrix. Furthermore, the addition of Ni will result in a more uniform distribution of Fe and facilitate the formation of the ferromagnetic Ni3Fe phase. In this study, Cu100−xFex and Cu100−x(Ni3/4Fe1/4)x series films were prepared by magnetron sputtering technique. The magnetic properties of films are closely related to their ferromagnetic element content. An increase in the content of ferromagnetic elements leads to an improvement in the saturation magnetization (MS) strength and a decrease in the coercivity (HC). The formation of Fe-Fe pairs is more favorable for magnetic properties compared to Ni-Fe pairs. Meanwhile, by comparing with bulk alloys, the distribution of the magnetic elements severely affects the magnetic properties. Moreover, the resistivity of Cu100−xFex films (20.3–96.7 μΩ cm) is much higher than that of Cu100−x(Ni3/4Fe1/4)x films (15.6–60.6 μΩ cm), which depends on the magnetic properties. This study systematically analyzes the effect of the content and distribution of magnetic elements on magnetic and electrical properties.

Co-Optimization of a-InGaZnO Framework for Enhancing Thin Film Transistors Stability and Electrical Properties

Co-Optimization of a-InGaZnO Framework for Enhancing Thin Film Transistors Stability and Electrical Properties

Effect of doping on the structural, optical and electrical properties of TiO2 thin films for gas sensor

Effect of doping on the structural, optical and electrical properties of TiO2 thin films for gas sensor

Electrical properties of AgNbO3 thick films by aerosol deposition followed by post-annealing in oxygen atmosphere

Electrical properties of AgNbO3 thick films by aerosol deposition followed by post-annealing in oxygen atmosphere

Combined effects of substrate temperature and post annealing temperature on structural, optical and electrical properties of Sb-doped SnO2 films

Sb-doped SnO2 (ATO) films have received extensive attention as transparent conductive films, but there is still a lack of in-depth and systematic study on combined effects of substrate temperature (Ts) and annealing temperature (Ta) on their transparent conductive properties. In this study, ATO films were prepared using RF magnetron sputtering at RT∼400 ℃ and subsequently annealed at 200–1000 ℃. The results show that the conductive properties of the films enhance (with a decrease in resistivity from 1.15×10-1 to 2.15×10-3 Ω•cm) and the average visible-light transmittance (TVis) decreases (90.16 → 38.24%) with increase of Ts. With the increase of Ta, the conductive properties of the films prepared at different Ts tend to first enhance and then degrade, and the TVis basically shows a trend of first decreasing and then increasing. After annealing at 600 ℃, the films prepared at RT and 100 ℃ can achieve better comprehensive properties (resistivity of 2.50×10-3 and 1.64×10-3 Ω•cm, carrier concentration of 3.35×1020 and 4.93×1020 cm-3, mobility of 7.73 and 7.76 cm2/V•s, sheet resistance of 84 and 55 Ω/sq., and TVis of 86.63 and 79.50%). In order to explore the intrinsic mechanism of the optical and electrical performance of ATO films changing with Ts and Ta, the preferred orientation, crystallinity, and stress state of the films were analyzed by XRD, and their surface morphology was observed by SEM. Meanwhile, the chemical states of Sn, O and Sb as well as Sb content in the films were analyzed by XPS, and their lattice vibration modes of the film were studied by Raman spectra. Finally, the process-structure-properties correlations were established for the ATO films.

Advancement of electro-optical properties through changes in the physicochemical composition of hybrid thin films by doping reduced graphene oxide into a sol-gel process solution.

A hybrid thin film was fabricated by doping graphene oxide into a sol-gel solution containing a mixture of zirconium, bismuth, and indium oxide. The thin film was fabricated using a brush coating process. The graphene oxide doping ratios used were 0, 5, and 15 wt%. During the thin film fabrication process, the produced sol-gel solution generates a contractile force due to the shear stress of the brush bristles, resulting in a microgroove structure. This structure was confirmed through scanning electron microscopy analysis, which revealed the clear presence of rGO. Comparing the electrical properties of a zirconium bismuth indium oxide thin film without graphene oxide doping and a thin film doped with 15 wt% graphene oxide, the electro-optical properties were significantly improved with graphene oxide doping. In general, the threshold voltage decreased by approximately 0.42 V. In addition, bandgap measurements confirmed the improved conductivity characteristics with graphene oxide doping. Since this improvement in electro-optical properties is associated with the reduction process due to graphene oxide doping, X-ray photoelectron spectroscopy analysis was performed to assess the intensity change of each element. Based on these observations, hybrid thin films doped with graphene oxide emerge as promising candidates for next generation thin film.

Effect of particle size on optical and electrical properties of thin films – a simulation approach

This paper presents a simulated investigation of the relationship between surface roughness and particle size as well as the resulting impact of the both on the thin film’s physical and optical properties. Non-porous thin films are created through computer simulation for a range of particle sizes following the random deposition with a surface relaxation approach. For the deposited thin films different fundamental parameters like transmittance, reflectance, absorption coefficients, frequency dependent dielectric constants, loss angle, refractive indices, optical band gap have all been calculated and in this process of calculation the fundamental values of two different materials; zinc oxide (ZnO and cadmium selenide (CdSe) are taken. It has been seen that when the particle sizes are comparable the calculated values of optical band gap of both ZnO and CdSe matches well with the experimental values of the same reported by others. This is probably the first effort to develop a direct relation between the particle size with different fundamental optical properties of different materials through simple simulation which agrees well with the experimental result. This would definitely help the experimental researchers in the field of material science to design their experiments as per the desired requirements.

Cu-doped NiO thin film's structural, optical, and electrical properties and its negative absorption behaviour in the Infra-Red region

NiO undoped and Cu-doped thin films on FTO-coated glass (fluorine-doped tin oxide) are prepared by employing the sol-gel spin coating method. The Cu-doping effect was observed in all the characterized reports such as absorption, transmittance, field emission scanning electron microscope (FESEM), Grazing Incidence X-ray Diffraction (GIXRD), photoluminescence (PL), Raman spectra, current-voltage measurement (IV), and X-ray photoelectron spectroscopy (XPS). Enhancement in electrical conductivity due to Cu doping and IR illumination has been found. Band gap can also be tuned by varying doping concentrations. One new phenomenon called negative absorption (NA) has been found while investigating the optical properties in the infrared (IR) region for both undoped and Cu-doped NiO on the FTO substrate, which opens a new door for advanced research. The multifarious properties of NiO thin films offer various applications in many different fields.

Электрофизические и температурные характеристики тонких слоёв квантовых точек Ag2S

This paper presents a study of the electrical properties of colloidal silver sulfide quantum dots thin films (Ag2S/SiO2 QDs) and silver sulfide quantum dots decorated with Au plasmon nanoparticles (Ag2S/SiO2/Au QDs). A study of the conductivity temperature dependences was carried out in the temperature range from 300 to 360 K. The activation energy values were obtained from linear approximations of the current-voltage characteristics in Arrhenius coordinates. It has been shown that decorating Ag2S/SiO2 QDs with Au plasmon nanoparticles leads to an increase in the band gap from 0.29 to 0.89 eV. In this work, the ideality factor is calculated and the main conductivity mechanisms of the presented thin-film structures are determined. It has been shown that decorating Ag2S/SiO2 QDs with Au plasmon nanoparticles leads to a change in the conductivity type. According to the Mott-Gurney model, the charge carriers mobility is calculated.

Investigations of In2O3 Added SiC Semiconductive Thin Films and Manufacture of a Heterojunction Diode

This study involved direct doping of In2O3 into silicon carbide (SiC) powder, resulting in 8.0 at% In-doped SiC powder. Subsequently, heating at 500 °C was performed to form a target, followed by the utilization of electron beam (e-beam) technology to deposit the In-doped SiC thin films with the thickness of approximately 189.8 nm. The first breakthrough of this research was the successful deposition of using e-beam technology. The second breakthrough involved utilizing various tools to analyze the physical and electrical properties of In-doped SiC thin films. Hall effect measurement was used to measure the resistivity, mobility, and carrier concentration and confirm its n-type semiconductor nature. The uniform dispersion of In ions in SiC was as confirmed by electron microscopy energy-dispersive spectroscopy and secondary ion mass spectrometry analyses. The Tauc Plot method was employed to determine the Eg values of pure SiC and In-doped SiC thin films. Semiconductor parameter analyzer was used to measure the conductivity and the I-V characteristics of devices in In-doped SiC thin films. Furthermore, the third finding demonstrated that In2O3-doped SiC thin films exhibited remarkable current density. X-ray photoelectron spectroscopy and Gaussian-resolved spectra further confirmed a significant relationship between conductivity and oxygen vacancy concentration. Lastly, depositing these In-doped SiC thin films onto p-type silicon substrates etched with buffered oxide etchant resulted in the formation of heterojunction p-n junction. This junction exhibited the rectifying characteristics of a diode, with sample current values in the vicinity of 102 mA, breakdown voltage at approximately −5.23 V, and open-circuit voltage around 1.56 V. This underscores the potential of In-doped SiC thin films for various semiconductor devices.