Radio Frequency Magnetron Sputtering Research Articles

Enhancement of crystallinity and the optical properties in gamma irradiated and thermally annealed cobalt doped MgTiO3 thin films

We report the crystal structure, surface morphology and optical properties of gamma (γ) irradiated, and thermally annealed cobalt (5%) doped magnesium titanate thin films. Mg0.95Co0.05TiO3 (MCT) thin films were fabricated on quartz substrates by Radio Frequency magnetron sputtering while substrate temperature was maintained at 300°C. Firstly, the as-prepared MCT thin films were irradiated by 1.33 MeV 60Co γ – rays with varying doses in the range of 0 – 125 kGy with the intervals of 25 kGy and post-annealing process at 700°C. The X-ray diffraction pattern of irradiated thin films is amorphous, whereas annealed films are crystalline, which are refined with the Rietveld refinement method by considering the R3¯space group. Dominated crystallite size (39 nm) with low strain is identified for the samples exposed at 75 kGy. In addition to the γ-irradiation of 75 kGy, the optical characteristics revealed that an enhanced bandgap (∼ 4.27 eV) and refractive index (2.26) had been observed for an annealed sample as compared with the bandgap (∼ 3.68 eV) and refractive index (2.10) of as-deposited sample. The influence of γ-irradiation dose and annealing on MCT thin films' structural and optical properties has been discussed. This study demonstrates that the γ–ray irradiated MCT films are potential candidates for anti-reflection coating applications.

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.

Study on mechanical properties of ZnO/Si interface under thermal shock

Influence of thermal shock on ZnO/Si interfacial mechanical properties was studied through experiments, molecular dynamics simulations and machine learning prediction. ZnO films were deposited onto silicon wafers by radio frequency magnetron sputtering and then suffered different times of thermal shock. The experimental results show the adhesion strength of ZnO/Si interface is relatively stable under thermal shock. XRD and simulation illustrate the interfacial reactions of Si based films could experience strong interaction through Si, Zn and O atoms located at ZnO/Si interface during thermal shock, which could explain the stability of the interface. The machine learning prediction indicates the mechanical properties of ZnO/Si interface are still relatively stable after more thermal shocks. The obtained conclusions are hoped to be helpful for the understanding of ZnO/Si properties under thermal load and to guide the design of related devices in energy field.

Temporary change in NEXAFS spectra of amorphous carbon nitride films with photoinduced deformation by visible light irradiation

Amorphous carbon nitride (a-CNx) films, prepared by reactive radio frequency magnetron sputtering, exhibit unique characteristics under visible light irradiation, referred to as photoinduced deformation. This phenomenon represents an energy conversion system wherein photon energy transforms into kinetic energy. The chemical bonding structure of a-CNx films was analyzed using near-edge x-ray absorption fine structure (NEXAFS) at the NewSUBARU synchrotron facility of the University of Hyogo, Japan. This analysis aimed to elucidate the mechanisms behind the photoinduced deformation observed in a-CNx films. Three variants of a-CNx films, displaying varying degrees of photoinduced deformation, were deposited using a graphite target and nitrogen gas under different deposition temperatures. The NEXAFS spectra of the a-CNx films with substantial photoinduced deformation showed changes under light irradiation from a Xe lamp (directed through an optical window within the NEXAFS chamber). Specifically, the peaks corresponding to the 1s to π* transition related to C—C and 1s to σ* transition related to C—N bonds exhibited high sensitivity to visible light irradiation. Simultaneously, the N K-edge spectra associated with the 1s to π* transition, attributed to the N—C bond, exhibited a slight intensity decrease. Conversely, the C K-edge spectrum in the a-CNx films displaying minimal photoinduced deformation remained unchanged under visible light irradiation. The N K-edge spectra maintained a consistent shape under both visible light and dark conditions.

Study on the film-forming properties of Mo–Na ceramic targets

In order to provide sufficient and stable Na+ for the CIGS flexible thin film solar cells, Mo–Na ceramic targets were prepared by the plasma-assisted cold sintering process (CSPS). And the film-forming properties of the Mo–Na targets were studied. The Mo–Na targets were prepared with MoO3 as precursor. The Mo–Na targets were successfully prepared with uniformity, compactness and high relative density (98.19 %). Then, the Mo–Na monolayer films were prepared by radio frequency (RF) magnetron sputtering. The results show that Mo–Na monolayer films are homogeneous and compact. Significantly, abundant Na+ are stored in the Mo–Na monolayer films. To verify the application of Mo–Na targets in the CIGS cells, the sandwich structure (Mo/Mo–Na/Mo) films and co-sputtered films were studied. The results show that the co-sputtered films have sufficient Na+, and show good photoelectric and mechanical properties. In addition, after heat treatment, Na+ can diffuse to the surface of the sandwich films, which can provide sufficient and stable Na+ for CIGS thin film cells.

ZnO-based triboelectric nanogenerator and tribotronic transistor for tactile switch and displacement sensor applications

Tribotronics, the coupling of triboelectricity and semiconductors, is a novel field that has sparked much interest in the nanoelectronics and nanoenergy industries. This work presents the fabrication of a ZnO tribotronic transistor by combining a ZnO thin film transistor (ZnO-TFT) and a triboelectric nanogenerator (TENG) operating in vertical contact separation mode. A Si/SiO2/ZnO/Au structure was used to construct a bottom-gated ZnO-TFT. Radiofrequency (RF) magnetron sputtering was employed to deposit ZnO thin film, and the Au contact was achieved through thermal evaporation. A range of annealing temperatures was investigated, and ZnO TFT annealed at 500 °C exhibited a maximum electron mobility of 5.47 cm2/V s and a high on/off ratio of 105. We also investigated the photoresponse of this optimized ZnO-TFT using a UV LED. A vertical contact separation mode TENG was fabricated using ZnO (tribo-positive layer) and polyvinylidene difluoride (PVDF, tribo-negative layer) and combined with the ZnO TFT to fabricate a tribotronic transistor. The drain current of the tribotronic transistor dropped from 2.9 to 0.02 µA at a drain voltage of 5 V when the tribo layers were separated by 15 mm. Within the separation region of 2 mm, the device showed a 1.29 µA/mm change in drain current demonstrating its effectiveness in displacement sensing. Unlike conventional TFTs, the TENG's output could successfully control the tribotronic transistor's drain current and was innovative in such domains where conventional electrical components were constrained. Furthermore, this ZnO tribotronic device was used as an active smart tactile switch by simply touching or releasing the ZnO TENG with a finger.

ZrO2-CeO2/WO3 heterostructure films prepared by magnetron sputtering for humidity-tolerant triethylamine sensing

Up to now, the development of gas sensors based on metal oxide semiconductors (MOSs) that can detect triethylamine (TEA) under high humidity conditions remains a significant challenge. In this study, we present the ZrO2-CeO2/WO3 (ZCW) heterostructure films for TEA detection under high relative humidity, which were prepared by co-sputtering ZrO2 and CeO2 onto the surface of a WO3 film using the radio frequency magnetron sputtering method. The gas sensors based on the ZCW heterostructure films exhibited outstanding TEA-sensing performance, including high response (18.56–20 ppm), rapid response/recovery rate (1/5 s), excellent selectivity, wide detection range (0.5–500 ppm), outstanding reproducibility and stability, and ideal anti-humidity ability. The excellent TEA-sensing properties of the ZCW heterostructure films should be mainly attributed to their unique surface microstructure, abundant oxygen vacancies, and the formation of heterostructures between ZrO2, CeO2, and WO3. Compared to the WO3 film, both the CeO2/WO3 and ZrO2-CeO2/WO3 films demonstrated highly-enhanced humidity-tolerant performance, which should result from the redox reactions between the Ce3+ and Ce4+ ions. This study provides a general method for preparing the MOSs-based TEA sensors that could work under high humidity condition.

The effects of oxygen flow ratio on the properties of Ag x O thin films grown by radio frequency magnetron sputtering.

The Ag x O thin film with various oxygen flow ratios (R[O2]%) deposited by radio frequency magnetron sputtering (RFM-SPT) has been studied. While adjusting R[O2]% from 0% to 30%, the Ag x O thin film transitioned from metal to semiconductor and/or insulator with different transparent appearances on the surface observed using X-ray diffraction (XRD) and transmittance measurement. At high oxygen flow ratios, the Ag x O film is multi-phased as a mixture of Ag(II)O and Ag2 (III)O3. In addition, the work function (ϕ) of those samples changes from 4.7 eV to 5.6 eV as measured by photoelectron yield spectroscopy (PYS). The compositional and chemical state changes that occur at the Ag x O surface during the increments of R[O2]% are evaluated by the relative peak intensities and binding energy shifts in X-ray photoelectron spectroscopy (XPS). With the incorporation of more electrons in chemical bonding, the oxygen-induced band forms. And combining all the results from transmittance (band gap confirmation), PYS (work function confirmation), and XPS (valence band position confirmation), the estimated band diagrams are given for the oxidation state of Ag x O with various oxygen flow ratios.

Effect of substrate temperature and position on properties of Cu3N thin films deposited by reactive radio frequency magnetron sputtering

Copper nitride (Cu3N) thin films were deposited on soda lime glass (SLG) substrates by reactive radio frequency (RF) magnetron sputtering using a pure Cu target in the presence of argon and nitrogen. The structural, optical, and electrical properties of the Cu3N films were investigated systematically on substrate temperature and position, demonstrating that both parameters strongly influence the properties of Cu3N thin films. XRD patterns revealed the formation of the Cu3N phase at all substrate temperatures and positions. The transmittance of the Cu3N thin films was over 80 % in the transparent region and the band gap for Cu3N was determined to 1.7–1.9 eV with a very high absorption coefficient above 104 cm−1. The n-type conductivity was observed in every Cu3N film but the resistivity varied considerably with both substrate temperature and position. The promising physical properties of Cu3N thin films suggest their potential application in optoelectronic devices such as thin film solar cells.

A novel refractive index based-fiber optic sensor for milk adulteration detection

Milk adulteration poses a significant risk to public health and consumer trust, compromising its nutritional value. To address this, we've developed an optical fiber-based sensor using a Lossy Mode Resonance (LMR) approach. Antimony Oxide (Sb2O3) serves as the sensing layer, deposited onto the optical fiber's unclad core using Radio Frequency Magnetron sputtering. The sensing layer underwent comprehensive characterization, including X-Ray diffraction (XRD), UV–Vis spectroscopy, Ellipsometer, Atomic Force Microscopy (AFM), EDAX, and Field Emission Scanning Microscopy (FESEM). The sensor was tested for formaldehyde and water adulteration across normal milk type 1, full-fat milk type 2, vendor milk type 3, and, with concentrations ranging from 0 % to 10 %. Observations included resonance wavelength shifts and sensing parameters such as sensor response, sensitivity, and repeatability. For Sb2O3-coated sensor probes, responses to formaldehyde and water adulteration for type 1 milk is 2.05 % and 2.22 %, type 2 milk is 2.17 % and 2.4 %, and type 3 milk is 1.90 % and 1.95 %. Sensitivity for Sb2O3-coated probe to formaldehyde are 2.2 nm/v% (type 1 milk),1.9 nm/v% (type 2 milk) and 1.5 nm/v% (type 3 milk). For water in milk, the sensitivities are 1.7 nm/v%, 1.5 nm/v%, and 1.2 nm/v%. Furthermore, a prototype sensor probe has been developed for continuous milk adulteration monitoring, interfaced with Arduino and Thing Speak.

Staggered band alignment of n-Er2O3/p-Si heterostructure for the fabrication of a high-performance broadband photodetector

The low responsivity of conventional Silicon photodiodes in ultraviolet and near-infrared regimes restricts their utility as broadband photodetectors (BBPDs). Despite ongoing investigations into various p-n heterostructures for Silicon-based BBPDs, challenges such as high dark current (Idark), low collection efficiency, low detectivity, and compatibility issues with large-scale Silicon-based devices persist. In this context, we have fabricated relatively unexplored n-Er2O3/p-Si heterojunction-based BBPDs. Polycrystalline Er2O3 thin films (∼110 nm) were deposited on p-Si 〈100〉 substrates by radio frequency magnetron sputtering. Although this process induces a microstrain of approximately 0.022 and a dislocation density of about 0.00303/nm2, the presence of optically active defects is minimal, indicated by a low Urbach energy (∼0.35 eV). X-ray photoelectron spectroscopy (XPS) analysis confirms staggered band alignment at the heterointerface, facilitating efficient charge carrier separation and transport. Consequently, the In/p-Si/n-Er2O3/In device demonstrated significant BBPD properties– low Idark ∼0.15 μA (at +5 V), photo-to-dark current ratio (PDCR) ∼6.5 (at +5 V, 700 nm) with a maximum photoresponsivity ∼22.3 A W−1, and impressive detectivity (∼1013 Jones) even in UV-C region where traditional silicon-based photodetectors respond feebly. The device also demonstrates transient photo-response across an ultrawide spectrum (254 nm–1200 nm) with a fast rise time/fall time ∼79 ms/∼86 ms (at −5 V for 600 nm illumination). This work establishes a straightforward and reliable method for proper material engineering, surface texturing, staggered heterojunction formation, and high-performance BBPD fabrication with prominent broad-spectrum responsivity, sizeable detectivity, and fast response. The integration of these BBPDs with Silicon opens possibilities for their use in electronic devices containing optical switches for communications and broadband image sensors, enhancing their utility in various applications.

Development of room-temperature operable TiO2-x-based hydrogen gas sensor with light irradiation

In this research work, TiO2-x-thin films are deposited through a radio-frequency magnetron sputtering technique by varying the oxygen partial pressure (pO2) of 6.0 %, 6.4 %, and 6.8 %. The X-ray diffraction analysis depicts the formation of the anatase phase of the annealed thin film with a high crystalline nature. The existence of higher oxygen vacancies and surface roughness are confirmed by the X-ray photoelectron spectroscopy and the atomic force microscopy analyses, respectively, in the 6.0 % pO2 grown thin film. At room temperature (30 °C) and dark conditions, the optimized TiO2-x-based hydrogen gas sensor device depicts a notable response of 22.9 % on exposure to 100 ppm of H2 gas. The irradiation of the ultra-violet (UV) light (λ = 365 nm) on the sensing material promotes desorption of the oxygen species and hence improves the responsivity of the sample. The highest responsivity of 87.7 %, along with faster response and recovery time of 9.4 s and 7.8 s, respectively, is achieved under the UV light irradiation and 100 ppm of H2 gas for the sample grown at 6.0 % pO2, which signifies its potential for the development of room temperature operable hydrogen gas sensor.

Biological and Physicochemical Analysis of Sr-Doped Hydroxyapatite/Chitosan Composite Layers.

In this work results are presented on the evaluation of HAp, HApSr, HAp_CS, and HApSr_CS layers deposited on Ti substrates regarding L929 cell viability and cytotoxicity as well as antimicrobial activity against Staphylococcus aureus, in connection with their physicochemical properties. The HAp and HApSr layers generated by radio-frequency magnetron sputtering technique were further covered with chitosan by a matrix-assisted pulsed laser evaporation technique. During the plasma depositions, the Ti substrates were heated externally by a home-made oven above 100 °C. The HApSr_CS layers generated on the unpolished Ti substrates at 100 °C and 400 °C showed the highest biocompatibility properties and antimicrobial activity against Staphylococcus aureus. The morphology of the layer surfaces, revealed by scanning electron microscopy, is dependent on substrate temperature and substrate surface roughness. The optically polished surfaces of Ti substrates revealed grain-like and microchannel structure morphologies of the layers deposited at 25 °C substrate temperature and 400 °C, respectively. Chitosan has no major influence on HAp and HApSr layer surface morphologies. X-ray photoelectron spectroscopy indicated the presence of Ca 2p3/2 peak characteristic of the HAp structure even in the case of the HApSr_CS samples generated at a 400 °C substrate temperature. Fourier transform infrared spectroscopy investigations showed shifts in the wavenumber positions of the P-O absorption bands as a function of Sr or chitosan presence in the HAp layers generated at 25, 100, and 400 °C substrate temperatures.

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.

The effect of RF sputtering power on structural, nanomechanical and tribological properties of single layered TaN coatings

Single-layered TaN thin coatings were deposited on Ti6Al7Nb alloy substrates using reactive radiofrequency magnetron sputtering, with variations in target power. To assess the crystalline structure, chemical composition, and surface topography of these coatings, Grazing Incidence x-ray Diffraction (GIXRD), Energy Dispersive Spectroscopy (EDS), and Scanning Probe Microscopy (SPM) were employed, respectively. The study revealed that deposition power impacts the structure and composition of TaN coatings. Further analysis using x-ray Photoelectron Spectroscopy (XPS) indicated that the TaN coatings predominantly consisted of Ta and N, with trace amounts of oxygen (O 1s). Additionally, nanomechanical testing was conducted to evaluate hardness (H), modulus (E), and scratch properties. Results suggested that multiphase hex-TaN coatings exhibited superior H, E, and scratch properties compared to other cubic-structured TaN coatings. Friction and wear properties against steel balls under dry sliding conditions were determined using a ball-on-disk nanotribometer. The findings showed that mix-phase TaN coating exhibited a minimum coefficient of friction of 0.054 and a wear rate of 2.14 × 10−6 mm3/N.m. Abrasion, ploughing and oxidation were identified as the primary wear mechanism responsible for the wear of the TaN coatings.

Preparation of carbon/nickel composites by magnetron sputtering and study on electromagnetic shielding effectiveness

A pure nickel film and a carbon/nickel (C/Ni) composite film were produced using radio frequency magnetron sputtering. The structure of the films was regulated by adjusting the sputtering power and the time allocation of sputtering nickel and graphite targets. Furthermore, a scanning electron microscope, an x-ray diffractometer, and a Raman spectrometer were employed for sample characterization. The results demonstrated that the thickness of the pure nickel film and C/Ni composite film with a total deposition time of 60 s was between 44.96 and 65.31 nm. The nickel film exhibited preferential growth along the crystal plane (111), and the structure of carbon materials was in the second stage of the three-stage model known as “amorphization trajectory of graphite.” The prepared films’ electromagnetic interference shielding effectiveness (EMI SE) in the X-band was investigated using a vector network analyzer. It was observed that the C/Ni composite film with a thickness of 44.96 nm demonstrated a superior EMI SE with a maximum value reaching 21 dB. The EMI SE of the C/Ni composite film can reach the same performance and even exceed that of the pure nickel film obtained at the power of 200 W for 60 s in certain frequency segments. In conclusion, the pure nickel film can be replaced by C/Ni composite film prospectively due to their excellent EMI SE along with advantages such as reduced thickness, lighter weight, and lower cost.

Optoelectronic properties of perovskite thin films derived from lead sulfide via radio frequency magnetron sputtering: effect of the substrate temperature

Methylammonium lead iodide (CH3NH3PbI3; MAPbI3) films were fabricated from sputtered lead sulfide (PbS) films prepared at various substrate temperatures according to the Thornton structural zone model. PbS films were converted to lead iodide (PbI2) and finally to MAPbI3 in a two-step gas-phase reaction. The increase in substrate temperature caused the morphology to change to fibrous interconnected grains, which played an important role in improving the optoelectrical properties of perovskite films. Moreover, enhanced charge transport of MAPbI3 films was observed owing to the fibrous interconnected PbI2 precursor, which was confirmed by a higher absorption coefficient and longer carrier lifetime.

The anomalous Hall effect in the epitaxial-grown semiconducting CuCo2O4 thin film

The high-quality inverse spinel CuCo2O4 thin films are epitaxially grown on (001) MgAl2O4 substrates by radio frequency magnetron sputtering. The electrical transport properties exhibit typical semiconducting characteristics, accompanying the enhancement of resistivity with the thinning of CuCo2O4 thickness. The transport properties could be well understood by the Mott variable range hopping model. The anomalous Hall effect with a clear hysteresis loop is observed below 100 K, indicating the existence of out-of-plane magnetization in the epitaxial-grown CuCo2O4 films. In addition, the negative magnetoresistance at low temperature reverses to the positive magnetoresistance (≥100 K), which is related to the changes from the decrease in spin/carrier scattering under the magnetic field at low temperature to the enhancement of carrier deflection due to the conventional Lorenz force (≥100 K). The observed physical properties are closely related to the orbital occupation of Cu ion in CuCo2O4 films, which is a significant difference compared to that of documented metallic NiCo2O4. This work is a good comprehensive study of inverse spinel oxide thin films.

Microstructural and optoelectronic properties of sputtered Al:ZnO films and Al:ZnO/Cu bilayer structures: Effects of substrate and Cu thickness

In this study, using a multi-source confocal radio frequency magnetron sputtering system, we synthesized aluminum doped zinc oxide (AZO) single layers and AZO/Cu bilayers on glass and crystalline quartz substrates with a constant AZO thickness of 65 nm and variable Cu bottom layers with a thickness of 4–13 nm. The microstructural, morphological, optical, and electrical characteristics of all samples were investigated using a variety of spectroscopic techniques. The X-ray diffraction results show that all films prepared on both substrates have a hexagonal wurtzite crystal structure and exhibit the preferred orientation along the (002) plane with some microstructural variations. The atomic force microscopy images revealed that the thickness of the Cu layer and substrate type greatly affect the films' topography and surface roughness. The transmittance spectra indicate that the single AZO layer on both substrates possess the highest average visible transmission; however, all the samples deposited on glass substrates show greater transmittance than that on quartz. Photoluminescence analysis put into evidence a decrease in ultraviolet emission with Cu thickness for both substrates, with intensities varying according to substrate type. Hall Effect measurements reveal that all samples have n-type conductivity as well as that Cu thickness has a significant impact on their electrical characteristics. Moreover, a higher value of the figure of merit is achieved with the AZO/Cu bilayer structure grown on a glass substrate with 13 nm of Cu layer thickness.

Tuning the Topo-Morphological properties of ITO Films using Al-Ag interlayer for Low-Resistance Optoelectronics Devices

Indium tin oxide (ITO) is recently attracting intense attention for application as transparent conducting electrode in different optoelectronic devices including solar cells, liquid crystal displays and organic light emitting diodes. This is attributed to their high optical transmittance in the visible region and good electrical conductivity. In this work, surface topological-morphological (topo-morphological) and electrical properties of ITO based multilayer films with aluminum-silver (Al-Ag) metal interlayer (ITO/Al-Ag/ITO) are investigated after post annealing treatment at 300-500oC by atomic force microscopic (AFM), field emission scanning electron microscopy (FESEM), four-point probe and hall-effect techniques respectively. The ITO/Al-Ag/ITO films are deposited by direct current and radio frequency magnetron sputtering techniques on p-type Si at room temperature. The results showed a smooth surface topology by as-deposited film with films smoothness improving after post annealing treatment as analyzed by AFM method. Sharp crystallites peaks were obtained by all the films with smaller peaks diffusing and recombining to form larger films with increasing post-annealing temperature. The films root means square roughness increased as the temperature increases with film annealed at 500oC showing a superior and enhanced microstructure. Compared to as-deposited film, careful observation shows that surface morphology smoothness increased with increase in temperature with films annealed at 400oC and 500oC showing highest increasing surface smoothness pattern as determined by FESEM technique. Similarly, higher grain sizes are observed especially by films annealed at 400oC and 500oC due to the heat absorption which causes the particles to expand thereby narrowing the grain boundaries and subsequently improve the surface smoothness. These FESEM findings are consistent with AFM measurements confirming the high surface property and enhanced grain size with increasing post annealing temperature. The films exhibit decreased electrical resistivity and sheet resistance while carrier concentration and Hall mobility increased with increasing post annealing treatment indicating highest corresponding values of...