Roughness Of Thin Films Research Articles

Enhancing UV photodetection sensitivity via pulsed laser optimization in SnO2:WO3/Si nanostructures

Abstract This manuscript investigates the deposition of tin oxide (SnO2) doped tungsten trioxide (WO3) films on silicon (Si) substrate using pulsed laser deposition technique (PLD) for ultraviolet (UV) photodetection. The structural, optical, morphological, electric, and photodetector properties of SnO2 doped WO3 films were extensively investigated. The optical characteristics, using UV-Vis spectroscopy, reveals a tunable optical band gap ranging from 2.85 eV to 2.25 eV with increasing laser energy, which is consistent with the findings obtained from photoluminescence (PL) analysis. Raman spectroscopy demonstrates three vibration modes at 319.80, 603.30, and 866.20 cm-1. Field emission scanning electron microscopy (FESEM) images displayed spherical nanoparticles with average diameters of 43.90, 47.55, and 62.20 nm for 140, 180, and 220 mJ, respectively. Atomic force microscopy (AFM) measurements indicate an increase in the thin film grain size, roughness surface, and root mean square at higher laser energies (140, 180 and 220 mJ). Under illumination condition, the photodetector gives a considerable photocurrent amount (0.5 mA), which increases with higher laser energies. The proposed geometry demonstrates an excellent photo-response within the wavelength range of 350 to 550 nm, mainly at 420 nm. The optimized device illuminated with laser energy of 220 mJ exhibits a response and recovery time of 352 ms and 737 ms, respectively, highlighting its potential for efficient and responsive applications.

Preparation and Characterization of Nanostructured ITO Thin Films by Spray Pyrolysis Technique: Dependence on Annealing Temperature

Transparent conducting oxides (TCOs) like Indium tin oxide (ITO) have wide attention from all scientists which have low resistance and high visible light transmittance, used as transparent electrodes in many optoelectronic devices such as liquid crystal displays, touch screens, light emitting diodes, and solar cells. In this research, the relationship between the crystallization, optical transmittance, and surface roughness of nanostructured ITO thin films and the change in annealing temperature was investigated. To enhance the efficiency of this material in optoelectronic applications, both the optical transmittance in the visible region and the crystallite size must be increased. These results can be obtained by the heat treatment of the films. Nanostructured ITO thin layer films have been successfully prepared at a substrate temperature equal to (350)℃ by chemical spray pyrolysis (CSP) technique. The physical characterizations of nanostructured ITO thin layer films were investigated at different annealing temperatures (400,450 and 500)℃. The presence of diffraction peaks indicates that the as-deposited and post annealed films are polycrystalline cubic structure and the peak (400) is a preferred growth orientation. For all samples the value of intensity of diffraction peaks increases with increasing substrate temperature. The crystallite size of nanostructured ITO thin films is strongly related to the annealing temperature. The crystallite size estimated from XRD was found to rise with rising annealing temperature. The surface roughness of nanostructured ITO thin layer films increases with rising annealing temperature. High values of transmittance have been measured in the visible region 550 nm equal to (70, 82, 84 and 88)% corresponding to annealing temperature (350,400,450 and 500)℃ respectively.

A Preliminary Study on Structural and Optical Properties of Heat Treated Nb2O5 Nanostructure

Annealing is a heat treatment that alters the physical and sometimes chemical properties of a material to improve their crystalline structure and other important properties. This work presents the effect of post heat treatment on optical, structural, morphological, and surface roughness of Nb2O5 thin films at different temperatures (200-700oC) which to the best of our knowledge not been extensively studied yet. A clear modification in surface morphology and other studied properties was obtained. XRD results show a significant enhancement in the film’s structural properties such as a reduction in the dislocation densities and stress. The optical properties of the treated films show a clear decrease in the transmission and energy gap values which their values were found to reduce from (4.35 to 2.9) eV with heat treatment up to 600oC and re-increase at 700oC. The surface roughness was also enhanced as a result of increasing the grain size from (9.95 – 34.7) nm Finally, SEM images of the films show an obvious change in their morphology and an increase in film uniformity as a result of heat treatment. Therefore, heat treatment could be considered as a helpful method to control film characteristics. Main result should be presented quantitatively.

Evolution of TiAlSi thin film coatings under varying target power in DC magnetron sputtering

This study, for the first time, presents the growth, nucleation, and characteristics of TiAlSi thin films sputtered from a partially sintered Ti30Al16Si10 (at. %) composite target under controlled conditions of target power. The TiAlSi thin films were grown on soda-lime glass substrates through Direct Current (DC) sputtering at varying levels of the target power: 73.2 W, 151.2 W, and 269.5 W. The other deposition parameters: the deposition temperature, time, argon mass flow rate, substrate rotation, and deposition pressure, were kept constant at 23 °C, 150 min, 25 sccm, 5 rpm, and 10−3 mbar, respectively. The pre-sputter power, argon flow rate, and time were also kept constant at 73.2 W, 20 sccm, and 5 min, respectively. The physical properties, microstructure, crystal structure, topography, and mechanical properties of the thin film coatings were analysed. The thickness and rate of deposition of the TiAlSi thin films increased with an increase in the target power (73.2 W – 269.5 W) from 414.6 nm and 0.046 nm/s to 1358.8 nm and 0.151 nm/s, respectively. The chemical composition of all the thin films remained constant, with the formation of a uniform TiAlSi alloy with no segregation of elements. However, a thin (wetting) interlayer consisting of Si and O elements was observed between the TiAlSi layer and the glass substrate. Further, the structure sizes and roughness values of the TiAlSi thin films increased with an increase in the target power, with a maximum of 75.4 nm for the size and 4.78 nm for the RMS roughness of thin films deposited at the maximum target power (269.5 W). Lastly, mechanical analysis of the TiAlSi thin films depicted an increase in the hardness as the target power increased, with the highest hardness at maximum power (269.5 W) obtained as 4.76 GPa. Despite having the lowest elastic modulus (50.5 GPa), the coating deposited at the highest power exhibited the highest plasticity index (H/E) and plastic deformation factor (H3/E2) of 0.094 and 0.042 GPa, respectively, which indicated the high resistance to abrasive wear, cracking, and deformation, compared to thin films deposited at the lowest target power (H/E = 0.066 and H3/E2 = 0.015 GPa). This study demonstrates that target power is a significant factor in determining the growth of TiAlSi thin films during the sputtering process and can be used for better control of their physical, structural, and mechanical properties.

Low-temperature growth of CuS thin film on flexible substrates for photodetection

Abstract The covellite phase of copper sulfide thin film (CuS), owing to its excellent electronic, optical, and chemical properties, has attracted enormous attention in cutting-edge research. This research work emphasizes a comprehensive study of structural, optical, morphological, and electrical properties of CuS thin film deposited by chemical bath deposition (CBD) technique on flexible polyethylene terephthalate (PET) substrate at different deposition temperatures, i. e. 25 °C, 40 °C, 55 °C, and 70 °C for fabrication of flexible photodetector. XRD and Raman studies depict presence of hexagonal covellite phase (CuS), where as the RMS roughness of CuS thin film increases with a rise in deposition temperature. The optical bandgap of CuS thin film gets reduced with a rise in deposition temperature. The optimized CuS thin film, deposited at 70 °C, has exhibited a homogeneous surface with RMS roughness of 13.72 nm, mobility of 25.09 cm2/Vs, and bandgap of 1.86 eV. The mobility of CuS thin film is found to be increased with the rise in deposition temperature. The flexible CuS photodetector, deposited at 70 °C, has shown better photoresponse characteristics, exhibiting the highest responsivity of 0.18 mA/W, detectivity of 1.39×108 Jones, and sensitivity of 173.25 % upon light illumination. The photocurrent established possesses an outstanding dependence on various intensities of illuminated light. Furthermore, the bending test of flexible CuS photodetectors reveals the absence of any sign of deterioration up to a bending angle of 30°. The CuS thin film-based photodetector device exhibits the optimized photodetector device with reproducibility and steady photoresponse after bending. This suggests that the Al/CuS-PET/Al photodetector device could be used in various wearable optoelectronic device applications.

Impact of hydrogen plasma treatment on ITO substrate for enhanced performance of CdS/CdTe solar cells

The indium tin oxide (ITO) film was treated with 100 W-power hydrogen plasma for 5 min before being used as a substrate to fabricate thermally evaporated CdS thin films. The structural, optical, and electrical properties of ITO and grown CdS films affected by pre-deposition plasma treatment were studied. SEM images show that the surface of ITO film becomes smoother after treatment. AFM analysis determines a decrease and increase in the surface roughness of ITO and CdS thin films after treating the ITO substrate. The XRD patterns show an improvement in the crystallinity of the fabricated thin films. Increasing the optical energy bandgap up to 3.699 eV and.2.481 eV for ITO and deposited CdS films respectively. So, design simple CdS/CdTe solar cells at a device temperature of 300 K. Enhancing the photovoltaic parameters and an increment of about 20 % in solar cell performance.

Donor Defect Induced Ferromagnetism in Nb‐Doped ZnO Thin Films Grown by RF Magnetron Sputtering

The effect of Nb doping concentration (0, 1, 2, and 4 at. %) on donor defect‐induced ferromagnetism in ZnO thin films is investigated. The films are deposited on Si(111) substrates utilizing the radio frequency magnetron sputtering. X‐ray diffraction pattern unveils that the films show a pronounced orientation along the (002) direction. The relative intensities of defect‐related bands with that of the ultraviolet band from photoluminescence (PL) spectra show that 2 at. % Nb doping results in a greater number of donor defects (Zni+ and VO+) in the ZnO lattice. The parameters extracted from the electron paramagnetic resonance spectra follow a similar trend. The results from vibrating sample magnetometer measurement indicate that pure ZnO displays diamagnetic nature, whereas Nb‐doped ZnO exhibits a ferromagnetic nature. The saturation magnetization value is found highest for 2 at. % Nb doping, which correlates with the presence of a greater number of donor defects, as supported by the PL and electron paramagnetic resonance results. Images obtained from atomic force microscopy show that the surface roughness of the ZnO thin film reduces upon Nb doping. X‐ray photoelectron spectroscopy validates that Nb is doped in 2 at. % Nb‐doped ZnO thin film with Nb oxidation state of +5.

Effect of bias voltage on the structure and properties of CoCrFeNi high entropy alloy thin films prepared by magnetron sputtering

In this study, CoCrFeNi high entropy alloy thin films were prepared on 304 stainless steel and single crystal Si substrates using the direct-current magnetron sputtering process under different bias voltages. The effects of these bias voltages on the film micrographs, phase structure, surface roughness, corrosion resistance, and mechanical characteristics of thin films were studied by a scanning electron microscope, transmission electron microscope, X-ray diffractometer, atomic force microscope, electrochemical workstation and nanoindentation tester, respectively. The results indicated that all films exhibited equiaxed nano-scale grains and developed a columnar structure. Fe, Co, Cr, and Ni were uniformly dispersed in all films and all films displayed face centered cubic solid solution (FCC). At a bias voltage of 0 V, the CoCrFeNi HEAs film formed a FCC single phase. With increasing bias voltage, the crystallinity decreased and then increased, reaching the worst crystalline state at bias voltage of −200 V due to the fact that the structure of the film was composed of FCC nanocrystalline and amorphous biphasic structure. Meanwhile, the surfaces of the film prepared at bias voltage of −200 V exhibited the densest structures and the least roughness, with grain sizes reaching a minimum value of approximately 10 nm. In addition, columnar grains of the film prepared at a bias voltage of −200 V displayed the densest state and had the least size, thus this film displayed the best corrosion resistance of a minimum value 1.51 × 10−7 A/cm2, a maximum hardness of approximately 11.18 ± 0.2 GPa and a maximum elastic modulus of approximately 193 ± 2.8 GPa. The passivation films of CoCrFeNi HEAs films were mainly composed of Cr2O3.

Research on the improvement of the adhesion strength of the Cu films deposited on the Al2O3 films

Due to the significant discrepancy in the coefficient of linear thermal expansion between Cu and ceramic in T-type thin film thermocouples, the Cu thin films often exhibit a low adhesion strength with the ceramic layers (Al2O3). In order to improve the adhesion strength of the Cu with the Al2O3 films, several methods during preparation were studied. First, different thicknesses of the Cu thin films deposited at different deposition temperatures on the Al2O3 thin films prepared by the magnetron sputtering were studied. Second, the Ti/Ni buffer layer between the Cu and the Al2O3 thin films was prepared. Finally, the average roughness of Al2O3 was studied. The adhesion strength of the Cu with the Al2O3 thin films, the microstructure of the surface and the cross section of the Cu and the Al2O3 thin films, and the grain size and the roughness of the films are characterized by nanoscratch testing, scanning electron microscopy, and atomic force microscopy. The adhesion strength of the Cu films with the Al2O3 films increases with an increase in the thickness of the Cu thin films and the roughness of the Al2O3 thin films and the addition of the Ti/Ni buffer layers.

Zirconium oxide thin films deposited via DC magnetron sputtering: corrosion and morphological investigation

Purpose The purpose of this study is to investigate the structural, surface roughness and corrosion properties of the zirconium oxide thin films deposited onto SS304 substrates using the direct current (DC) magnetron sputtering technique. Design/methodology/approach DC sputtering at different powers – 80, 100 and 120 W – was used to deposit ZrO2 thin films onto different substrates (Si/SS304) without annealing of the substrate. Atomic force microscope (AFM), energy-dispersive X-ray spectroscopy (EDS), Tafel extrapolation and contact angle techniques were applied to investigate the surface roughness, chemical compositions, corrosion behavior and hydrophobicity of these films. Findings Results showed that the thickness of the deposited film increased with power increase, while the corrosion current decreased with power increase. AFM images indicated that the surface roughness decreased with an increase in DC power. EDS analysis showed that the thin film has a stoichiometric ZrO2 (Zr:O 1:2) composition with basic uniformity. Water contact angle measurements indicated that the hydrophobicity of the synthesized films decreased with an increase in surface roughness. Originality/value DC magnetron sputtering technique is infrequently used to deposition thin films. The obtained thin films showed good hydrophobic and anticorrosion properties. Finally, results are compared with other deposition techniques.

Sputter grown CuO thin films: Impact of growth pressure and annealing temperature on their microstructural architectures

High-quality copper oxide (CuO) thin films were deposited on the silicon (Si) substrate at the room temperature using the physical vapour deposition (PVD) technique named radio frequency (RF) sputtering. The copper-oxide thin-films were single crystalline and of uniform thickness. Subsequently, the influence of growth pressure (low gas pressure - 3 mTorr and high gas pressure - 100 mTorr) and post growth annealing at different temperatures (300 °C to 700 °C) were investigated to understand the microstructural and morphological changes of the thin film. With the influence of growth pressure and post thermal annealing temperature, significant changes in crystallinity, surface roughness, and surface oxidation rate of the CuO thin film were detected, which were adequately analyzed via several characterization techniques. X-ray diffraction (XRD) patterns revealed the phase formation with good crystallinity of the film, which is substantiated by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) characterization. Atomic force microscopy (AFM) images disclosed that the surface roughness of the film and grain size. By gaining insights into the structural and surface properties of CuO/Si thin films, this research presents new prospects for tuning of CuO phases, structures, and compositions for multifunctional applications.

The Effect of Annealing Temperature on the Surface Roughness and Crystal Structure of ZnO Thin Films Prepared by Electron Beam Evaporation Method on Glass Substrate

The Effect of Annealing Temperature on the Surface Roughness and Crystal Structure of ZnO Thin Films Prepared by Electron Beam Evaporation Method on Glass Substrate

Topography hierarchy of biocompatible polyhydroxyalkanoate film.

Polyhydroxyalkanoates (PHAs) are used for various biomedical applications due to their biocompatibility. Surface properties, such as surface roughness, are crucial for PHAs performance. Traditional parameters used for the characterization of surface roughness, such as R a, are often insufficient to capture the complex and hierarchical (multiscale) topography of PHA films. We measure the topography and surface roughness of thin PHA films with atomic force microscopy and analyze the topography data using several relatively novel data processing methods, including the calculation of autocorrelation functions, topological data analysis, and the distribution of minimum and maximum values of pixels over the topography data. The results provide details of multiscale and anisotropic surface properties that are crucial to PHAs biocompatibility but often overlooked by traditional topography analysis methods.

Catalytic synergy of WS2-anchored PdSe2 for highly sensitive hydrogen gas sensor.

Hydrogen (H2) is widely used in industrial processes and is one of the well-known choices for storage of renewable energy. H2 detection has become crucial for safety in manufacturing, storage, and transportation due to its strong explosivity. To overcome the issue of explosion, there is a need for highly selective and sensitive H2 sensors that can function at low temperatures. In this research, we have adequately fabricated an unreported van der Waals (vdWs) PdSe2/WS2 heterostructure, which exhibits exceptional properties as a H2 sensor. The formation of these heterostructure devices involves the direct selenization process using chemical vapor deposition (CVD) of Pd films that have been deposited on the substrate of SiO2/Si by DC sputtering, followed by drop casting of WS2 nanoparticles prepared by a hydrothermal method onto device substrates including pre-patterned electrodes. The confirmation of the heterostructure has been done through the utilization of powder X-ray diffraction (XRD), depth-dependent X-ray photoelectron spectroscopy (XPS) and field-emission scanning electron microscopy (FE-SEM) techniques. Also, the average roughness of thin films is decided by Atomic Force Microscopy (AFM). The comprehensive research shows that the PdSe2/WS2 heterostructure-based sensor produces a response that is equivalent to 67.4% towards 50 ppm H2 at 100 °C. The response could be a result of the heterostructure effect and the superior selectivity for H2 gas in contrast to other gases, including NO2, CH4, CO and CO2, suggesting tremendous potential for H2 detection. Significantly, the sensor exhibits fast response and a recovery time of 31.5 s and 136.6 s, respectively. Moreover, the explanation of the improvement in gas sensitivity was suggested by exploiting the energy band positioning of the PdSe2/WS2 heterostructure, along with a detailed study of variations in the surface potential. This study has the potential to provide a road map for the advancement of gas sensors utilizing two-dimensional (2D) vdWs heterostructures, which exhibit superior performance at low temperatures.

Impact of Cd/Sn molar ratio and annealing temperature on the properties of spin coated Cd2SnO4 thin films

We have synthesized and characterized spin coated Cd2SnO4 (CTO) thin films in the present work by varying the Cd/Sn = 2,3,4, and 5 M ratios, and 450 and 500 οC annealing temperatures. The structural studies were done using X-ray diffraction (XRD) and the results show that all the films exhibit a polycrystalline nature with (311) plane preferred orientation corresponding to Cd2SnO4 inverse spinel cubic phase. The morphological studies were done using an atomic force microscope (AFM) and field emission scanning electron microscope (FESEM). The thin films obtained with a roughness of 3–40 nm, and uniformly distributed grains without cracks are evident from the micrographs. The elemental analyses were carried out by employing EDAX and XPS techniques. The optical properties such as transmittance, bandgap, and refractive index are obtained using UV–Vis spectroscopy. The films were showing high transmittance (75–93 %) in the visible region. The band gaps of the investigated samples are found to be in the range of 3.4 eV–3.7 eV. The refractive index of CTO thin films in the 350–1000 nm wavelength range is around 1.7 to 1.9. The electrical properties show better results for the films annealed at 500 οC. The mobility values obtained are in the range of 0.6–4 cm2/Vs for different Cd/Sn ratio samples. The carrier concentration of CTO thin films is in the range of 4 × 1018 to 28 × 1018 cm−3. The presence of defects such as oxygen vacancy, Cd/Sn interstitial, and self-doping of Cd and Sn results in increased carrier concentration at higher Cd/Sn ratios. Besides, the wettability analysis was performed by contact angle measurements, which infer a hydrophobic to hydrophilic conversion in terms of the surface roughness of CTO thin films. From optoelectrical results, it is evident that the films exhibited better optical and electrical properties and are suitable for optoelectronic devices.

Studying the Crucial Physical Characteristics Related to Surface Roughness and Magnetic Domain Structure in CoFeSm Thin Films

This study investigated the effects of varying film thicknesses and annealing temperatures on the surface roughness and magnetic domain structure of CoFeSm thin films. The results revealed that as the film thickness increased, both the crystalline size and surface roughness decreased, leading to a reduction in coercivity (Hc) and improved magnetic contrast performance. Energy-dispersive X-ray spectroscopy (EDS) analysis confirmed the presence of cobalt (Co), iron (Fe), and samarium (Sm) within the thin films. Notably, the 40 nm Co40Fe40Sm20 thin film annealed at 200 °C exhibited lower sheet resistance (Rs) and resistivity (ρ), indicating higher conductivity and a relatively higher maximum magnetic susceptibility (χac) at 50 Hz. These findings suggest that these films are well suited for low-frequency magnetic components due to their increased spin sensitivity. The 40 nm Co40Fe40Sm20 thin film, subjected to annealing at 200 °C, displayed a distinct stripe domain structure characterized by prominently contrasting dark and bright patterns. It exhibited the lowest Hc and the highest saturation magnetization (Ms), leading to a significant improvement in their soft magnetic properties. It is proposed that the surface roughness of the CoFeSm thin films plays a crucial role in shaping the magnetic properties of these thin magnetic films.

Electrochemical anodization of cast titanium alloys in oxalic acid for biomedical applications

Titanium and its alloys have numerous biomedical applications thanks to the composition and morphology of their oxide film. In this study, the colorful oxide films were formed by anodizing cast Ti-6Al-4V and Ti-6Al-7Nb alloys in a 10% oxalic acid solution for 30 s at different voltages (20–80 V) of a direct current power supply. Atomic force microscopy was used as an accurate tool to measure the surface roughness of thin films on the nanometer scale. Scanning electron microscopy and X-ray diffraction were performed to analyze surface morphology and phase structure. According to the results, the produced titanium oxide layer showed high surface roughness, which increased with increasing anodizing voltage. The impact of anodizing voltages on the color and roughness of anodized layers was surveyed. The corrosion resistance of the anodized samples was studied in simulated body fluid at pH 7.4 and a temperature of 37 °C utilizing electrochemical impedance spectroscopy and the potentiodynamic polarization method. The anodized samples for both alloys at 40 V were at the optimal voltage, leading to a TiO2 layer formation with the best compromise between oxide thickness and corrosion resistance. Also, findings showed that TiO2 films produced on Ti-6Al-7Nb alloys had superior surface roughness properties compared to those of Ti-6Al-4V alloys, making them more appropriate for orthopedic applications. From the obtained data and the fruitful discussion, it was found that the utilized procedure is simple, low-cost, and repeatable. Therefore, anodization in 10% oxalic acid proved a viable alternative for the surface finishing of titanium alloys for biomedical applications.

Investigation of the hydrophilic nature and surface energy changes of HfO2 thin films prepared by atomic layer deposition

The wettability of metal oxides, which is directly related to the surface free energy (SFE), is used in a wide range of robust functional coatings, from hydrophilic to hydrophobic. Because wettability is significantly affected by solid surface properties, several studies on the determinant factors and their correlations have been conducted through the thin-film coating of metal oxides. Herein, we found that HfO2 thin films deposited via atomic layer deposition (ALD) are intrinsically hydrophilic. Simultaneously, a thickness-dependent wettability change is observed. These observations were investigated by measuring water contact angles (WCAs), film surface compositions, roughness, morphologies, and microcrystalline structures of the ALD-grown HfO2 thin films. It was deduced that the surface oxygen species significantly affected the intrinsic hydrophilicity of HfO2 thin films. In addition, the crystalline orientations evolved with film thickness, and thermal annealing was used to determine the thickness-dependent WCA trend. In particular, the transformation of the preferred m(-111) crystal orientation with a low SFE had a dominant impact on the SFE change in the HfO2 thin films. Considering the lack of fundamental studies on the SFE of ALD-grown HfO2 thin films, we believe that this study will help understand the wettability of HfO2 and its overall surface science.

Investigation on the influence of Zn content on the structural, optical, morphological and electrical properties of ternary compound Cd1−xZnxS window layer for CdTe solar cell

Ternary compound Cd[Formula: see text]Zn[Formula: see text]S thin films with different zinc compositions were deposited by the chemical bath deposition method, as a window layer for CdTe solar cells. The influence of Zn content on the structural, optical, morphological and electrical properties of Cd[Formula: see text]Zn[Formula: see text]S was studied from X-ray diffraction (XRD), SEM and UV-vis spectroscopy. We have considered the transformation of the crystal phase, change in the crystallite size and lattice parameters of Cd[Formula: see text]Zn[Formula: see text]S thin film with the change of Zn content through XRD studies. SEM measurement revealed that the size of Cd[Formula: see text]Zn[Formula: see text]S particles and surface roughness of thin film decreases with the increase of Zn composition. It was found that the band gap value obtained from transmittance spectrum became wider with the increase of Zn contents, which indicates the increase of film transmittance. The electrical resistivity of Cd[Formula: see text]Zn[Formula: see text]S thin films increased as Zn content [Formula: see text] increases. Finally, we measured the performances of CdTe solar cells using Cd[Formula: see text]Zn[Formula: see text]S thin films as a window layer and confirmed that desirable Zn content was in the range [Formula: see text] = 0.5-0.6.

Experimental study on heat transfer performance using a hybrid cooling method combined of a flat-plate heat pipe and spray cooling

A hybrid cooling system consists of spray cooling as condensing end and flat-plate heat pipe (FPHP) as heat-transfer medium was previously studied on the effects of the volume flow rate and the inlet temperature. As an extension, this paper using multi-nozzle arrays to promote the forced convection heat transfer and changing the surface roughness of the FPHP to improve the phase change heat transfer. It was found that the impinging energy and drainage channel formed by multi-nozzle arrays were the main reasons for the enhancement in convection region. However, in the phase-change section, a uniform thin liquid film and surface roughness apparently improved the evaporation and nucleate boiling. Relative to our previous study, a maximum heat flux removal was increased from 70 W/cm2 to 90 W/cm2 at surface roughness (Ra = 1.62 μm) with a surface superheat only 4.17℃, the heat transfer coefficient of 21.6 W·cm-2·K-1 and an enhancement of 28.6 % were obtained. Furthermore, the transition temperature and the temperature change rate were studied to explore the vapor flow modes and thermal response characteristics of the FPHP. As the transition temperature Ttr = 251 K, and the Knusden number＜0.01, the FPHP consistently maintained a continuum flow regime during startup, stabilization, and dry-out processes. Impressively, the temperature change rate of the FPHP remained below 0.015℃/s, resulting in a temperature change of only 0.9℃ within one minute. This exceptional temperature stability ensured reliable operation for electronic components.