Heterojunction Research Articles

UV‐Induced Degradation of Industrial PERC, TOPCon, and HJT Solar Cells: The Next Big Reliability Challenge?

With the surge of UV‐transparent module encapsulants in the photovoltaic industry aiming to boost quantum efficiency, modern silicon solar cells must now inherently withstand UV exposure. UV‐induced degradation (UVID) of nonencapsulated laboratory and industrial solar cells from several manufacturers is investigated. Passivated emitter rear contact (PERC), tunnel oxide passivating contact (TOPCon), and silicon heterojunction (HJT) cells can suffer from severe implied voltage degradation (>20 mV) after UV exposure relating to 3.8 years of module installation in the Negev desert. Front UV‐exposure causes more performance loss than an equal rear dose. This is connected to a higher UV transmission of the cell layers outside the bulk, indicating the photons need to reach the silicon surface to induce damage. Current–voltage measurements of the TOPCon groups most sensitive to UV degradation show more than 7%rel efficiency loss with the Voc as the main contributor. For two TOPCon groups, dark storage for 14 days after UV exposure causes an additional voltage drop on a similar scale as the UV damage itself, impeding straightforward reliability testing. UVID appears to be a complex process general to all dominant cell architectures with the potential to diminish efforts in efficiency optimization within only a few years of field employment.

Proton irradiation Of Ga2O3 Schottky diodes and NiO/Ga2O3 heterojunctions.

p-NiO/n-Ga2O3 heterojunction (HJ) diodes exhibit much larger changes in their properties upon 1.1MeV proton irradiation than Schottky diodes (SDs) prepared on the same material. In p-NiO/Ga2O3 HJ diodes, the narrow region adjacent to the HJ boundary is found to contain a high density of relatively deep centers with levels near EC-0.17eV and a depleted region in the immediate vicinity of the HJ boundary. The series resistance of the HJ diodes is slightly higher than for the Schottky diodes and shows a temperature dependence with activation energy ~ 0.12eV, like the temperature dependence of the NiO film resistivity. Irradiation with 1.1MeV protons leads to a decrease of the hole concentration in the NiO, with a high carrier removal rate of ~ 1.3 × 105cm-1 and a strong compensation of the interfacial region where the concentration of the EC-0.17eV centers decreases with a high rate of ~ 7 × 103cm-1. The combined action of these two effects gives rise to the much stronger increase of the series resistance of the HJ diodes compared to Schottky diodes. The observed differences between the radiation response of the HJs and SDs cannot be credibly attributed to the changes of the density of any of the deep electron and hole traps detected in our experiments.

The effect of single walled carbon nanotubes on conductivity and thermal properties of glass fiber reinforced composites

Abstract This paper reports on a comprehensive study of the effect of single-walled carbon nanotube (SWCNT) on the alternating current (AC) conductivity, thermal and morphological properties of the unsaturated polyester based glass fiber reinforced polymer composite (GFRPC). AC conductivity measurements were carried out using the impedance spectrum and thermal measurements were carried out using differential scanning calorimetry (DSC) at a temperature range of 24-900 °C and heating rates of 20 °C/min. Impedance results showed that the conductivity behavior in the nanotube-loaded composite laminate obeys a Jonscher-type mechanism. At low frequencies, the conductivity value remains almost constant for the doped material and takes the value of 10-5 S/cm. It is observed that the AC conductivity starts to increase after the critical frequency value of approximately 103 Hz and increases up to 10-2 S/cm due to hopping and tunneling mechanisms caused by space charge polarization accumulated in the local regions at high frequencies. The pure material with an insulating nature also exhibited a typical insulating behavior. Thermal testing showed that nanotube reinforcement increases thermal conductivity in three different directions. DSC thermocurves analysis also revealed that the addition of carbon nanotubes increased the glass transition temperature of the material from 180°C to 190°C. The scaling and fractal analysis methods were also applied to obtain hetero morphological structure of materials. The fractal analysis results indicated that carbon nanotube doping to the standard sample increases the coating rates, scalability and heterogeneity of the solid phase surface of the sample. The coating rates of composite surfaces were calculated as 45% and 36%, respectively. Morphology analysis revealed that the probability of finding surface particles for the nanotube-doped sample decreased compared to the undoped sample, but the fractal dimension value increased. While this value was 1.83 in the pure sample, it increased to 1.92 in the nanotube material.

ZnO/SnO2 based composite heterostructure for NO2 gas sensing properties

In recent years, interest in heterostructures and research on them has been increasing day by day. While semiconductors mainly exhibit different characteristics, they can exhibit different characteristics when they come together to form a heterostructure, and investigating the reasons for these is of great interest. For this purpose, in this study, such a hetero structure (ZnO/SnO2) was obtained by the Sol-Gel Dip Coating (SGDC) combined method and its effects on its characteristics against NO2 gas were tried to be examined.In this study, SnO2/ZnO composite heterostructures were grown by SGDC method. In this sense, this study is a first in the literature in terms of enlarging this structure with the SGDC technique. The number of SnO2 cycles was kept constant at 1 cycles and the ZnO layers were at different cycles as 1, 2, 3 and 5. The effect of ZnO cycles number on structural, morphological and most importantly NO2 gas detection properties was investigated in the formed heterostructures. In the XRD results, both ZnO and SnO2 peaks were observed and it was determined that these peaks belonged to the hexagonal wurtzite phase for ZnO and to the tetragonal rutile phase for SnO2. The lattice strain and crystallite size were calculated using Williamson-Hall and Scherrer method. The SEM images of ZnO-SnO2 manifest the change in the microstructure with increasing ZnO layer. The microstructure consisted of thin crystalline plates and small round-shape particles. The nano plates and walls shape and size changed with increasing ZnO layers. The operating temperature was defined as 165 °C for all sensors from NO2 gas sensing measurements. The responses of 1 ppm NO2 gas concentrations were calculated as 20 %, 201 %, 1078 % and 676 % for Z1S1, Z2S1, Z3S1 and Z5S1 heterosturucture respectively.

Correlation of interface structure and optical properties of Ga(N,As) and Ga(As,Bi) based type-II hetero structures

The type-II band alignment of particular III/V heterostructures is a promising route towards achieving certain wavelengths on specific substrates, which would not be possible with type-I structures. One example is telecommunication lasers on GaAs substrates. This study reports on the progress in combining dilute nitrides and dilute bismides in W-type hetero structures to improve the luminescence intensity, which is a fundamental prerequisite for future incorporation in a laser structure. Increasing the emission wavelength of these structures is challenging and the interface formation is critical, especially as two metastable materials are combined. Here, we investigate the impact of different interface configurations by growing Ga(N,As)/Ga(As,Bi) and Ga(As,Bi)/Ga(N,As) type-II structures. We employ metal–organic vapor phase epitaxy (MOVPE) to grow Ga(N,As) and Ga(As,Bi) layers and investigate the effects of interlayer thicknesses on the structural and optical properties of the hetero structures. The results indicate that − while the introduction of a GaAs interlayer can affect the direct and indirect transitions intensities − it does not significantly improve the interface quality. However, this is strongly influenced by the order in which the materials are grown. The growth of Ga(N,As) on Ga(As,Bi) shows no peculiarities, while the type II transition energy is shifted to lower energies when Ga(As,Bi) is grown on Ga(N,As). High-resolution X-ray diffraction (HR-XRD), photoluminescence (PL) spectroscopy, atomic force microscopy (AFM), and scanning transmission electron microscopy (STEM) were used to characterize the samples.

Carrier Scattering Analysis in AlN/GaN HEMT Heterostructures with an Ultrathin AlN Barrier

Experimental AlN/GaN heterostructures (HSs) with an ultrathin AlN barrier were obtained using molecular beam epitaxy with plasma activation of nitrogen. The layer resistance of the optimized structures was less than 230 Ω/¨. The scattering processes that limit the mobility of two-dimensional electron gas in undoped AlN/GaN HSs with an ultrathin AlN barrier have been studied. It is shown that in the ns range characteristic of AlN/GaN HEMT HSs (ns 1 × 1013 cm–2), a noticeable contribution to the scattering of charge carriers is made by the roughness of the heterointerface.

GeTe/MoTe2 Van der Waals Heterostructures: Enabling Ultralow Voltage Memristors for Nonvolatile Memory and Neuromorphic Computing Applications.

Advanced electronic semiconducting Van der Waals heterostructures (HSs) are promising candidates for exploring next-generation nanoelectronics owing to their exceptional electronic properties, which present the possibility of extending their functionalities to diverse potential applications. In this study, GeTe/MoTe2 HS are explored for nonvolatile memory and neuromorphic-computing applications. Sputter-deposited Ag/GeTe/MoTe2/Pt HS cross-point devices are fabricated, and they demonstrate memristor behavior at ultralow switching voltages (VSET: 0.15V and VRESET: -0.14V) with very low energy consumption (≈30 nJ), high memory window, long retention time (104 s), and excellent endurance (105 cycles). Resistive switching is achieved by adjusting the interface between the Ag top electrode and the heterojunction switching layer. Cross-sectional transmission electron microscope images and conductive atomic force microscopy analysis confirm the presence of a conducting filament in the heterojunction switching layer. Further, emulating various synaptic functions of a biological synapse reveals that GeTe/MoTe2 HS can be utilized for energy-efficient neuromorphic-computing applications. A multilayer perceptron is implemented using the synaptic weights of the Ag/GeTe/MoTe2/Pt HS device, revealing high pattern accuracy (81.3%). These results indicate that HS devices can be considered a potential solution for high-density memory and artificial intelligence applications.

Cryogenic temperature operation of NiO/Ga2O3 heterojunction and Ni/Au Schottky rectifiers

Vertical geometry NiO/Ga2O3 heterojunction (HJ) rectifiers and Ni/Au Schottky rectifiers fabricated on the same wafer and each with the same diameter (100 μm) were operated at 77–473 K to compare their capabilities in space-like environments. The HJ rectifiers suffer a 4-order reduction in forward current at 77 K due to the freeze-out of acceptors in the NiO, leading to MIS-type operation. By sharp contrast, the Schottky rectifiers have higher forward current and lower on-resistance at 77 K compared to 298 K due to improved carrier mobility. The on/off ratio of Schottky rectifiers at 77 K becomes similar to HJ rectifiers at 298–473 K. The reverse recovery time of Schottky rectifiers is reduced from 20 ns at 273 K to 16 ns at 77 K, while HJ rectifiers cannot be switched at this temperature. While the latter are superior for high-temperature applications, the former are better suited to cryogenic operation.

Investigation the Structure and Linear/Nonlinear Spectroscopic Performance of Fe:Co3O4/TiO2 Nanostructured Heterojunctions

Abstract The structure and linear/nonlinear spectroscopic performance of Fe:Co3O4/TiO2 (FCTO) nanostructured heterojunctions (HJs) were investigated. Pure TiO2 nanostructures and FCTO nanostructured HJs were synthesized by spray pyrolysis technique. The surfaces morphology of the samples was examined utilizing a scanning electron microscope. Energy-dispersive X-ray measurements were performed to confirm the content of the prepared FCTO HJs. The structures’ variations and bonding were explored with Fourier transform infrared spectroscopy. X-ray diffraction measurements were carried out to study the crystallinity, structures, and lattice parameters, revealing that the pure TiO2 nanostructures have a tetragonal crystalline structure with an anatase phase, while the Fe:Co3O4 layer possesses a cubic crystalline structure. XRD analysis also showed that the crystallite size increases from 15.9 nm (pure TiO2) to 25.4 nm (FCTO HJ). Optical performance was studied via UV-visible-NIR measurements. The optical parameters of the FCTO HJs were investigated and the nonlinear optical performance of the prepared samples was assessed. Great enhancement of the linear/nonlinear optical performance of the FCTO HJs was achieved compared with the pure TiO2 nanostructures. The results reveal that the Fe:Co3O4/TiO2 nanostructured HJs are recommended for many visible spectrum applications.

Numerical simulation of lead-free MASnI3 perovskite/silicon heterojunction for solar cells and photodetectors

Lead free n-type doped methyl ammonium tin iodide (MASnI3) perovskite/p-Silicon heterojunction (HJ) for solar cells and photodetectors are simulated using AFORS-HET automat simulation software. In the earlier work, lead based methyl ammonium lead iodide perovskite/silicon (n-MAPbI3/p-Si) heterojunction devices were studied. In view of the toxicity and environmental concerns related to lead, it is substituted with tin to make lead-free tin based perovskite to make n-MASnI3/p-Si HJ devices. Various parameters associated with the layers of MASnI3 perovskite and silicon wafer like, Band gap, thickness, doping concentration and texturing angle have been optimized. Various transparent conducting oxide (TCO) materials like indium tin oxide (ITO) and zinc oxide (ZnO) are used and its performance with ideal device is compared. Various metals are considered as front and back contact, to obtain best metals for each sides. This study investigates the potential of lead-free perovskite materials in solar cells, achieving a notable efficiency improvement compared to traditional lead-based counterparts. Our numerical simulations demonstrate that the optimized lead-free perovskite with structures, n-MASnI3/p-Si heterojunction can reach efficiencies of 27.2%. These findings suggest that lead-free perovskites could serve as a viable, environmentally friendly alternative in the photovoltaic industry.

Ultrafast Interfacial Charge Transfer in Anisotropic One-Dimensional CsPbBr3/Pt Epitaxial Heterostructure.

Colloidal one-dimensional (1D) perovskite nanorods (NRs) and metal epitaxial heterostructures (HSs) are the promising class of new materials for efficient photovoltaic and photocatalytic applications. Besides, fundamental photophysical properties and its device applications of 1D perovskite-metal HSs are limited due to their challenging synthetic protocols and difficulties in forming epitaxial growth between covalent and ionic bonds. Herein, we have synthesized the CsPbBr3 perovskite NRs-platinum (Pt) nanoparticles (NPs) (CsPbBr3/Pt) epitaxial HS using cation exchange followed by chemical reduction methods with the orthorhombic Cs2CuBr4 NRs. Here, the tertiary ammonium ions extensively helped to form the 1D Cs2CuBr4, CsPbBr3 NRs, and CsPbBr3/Pt HSs. For CsPbBr3/Pt HSs an epitaxial relationship has been established in the (020) plane of orthorhombic CsPbBr3 with the (020) plane of cubic Pt. Further, femtosecond transient absorption (TA) spectroscopy was employed to study the charge carrier dynamics of CsPbBr3/Pt HS. Upon 420 nm photoexcitation, excitons in the conduction band of CsPbBr3 NRs dissociate by electron transfer (with an ultrafast time of 1.1 ps) to the Pt domain. In addition, charge transfer (CT) was also demonstrated in the CsPbBr3/Pt HS, which is ascribed to strong electron coupling and epitaxial growth between CsPbBr3 and Pt states. This extensive understanding of the electron transfer dynamics of CsPbBr3/Pt epitaxial HS may pave the way to designing highly efficient photovoltaic and photocatalytic applications.

Flexible and Recyclable Bio-Based Polyester Composite Films with Outstanding Mechanical and Gas Barrier Properties Using Leaf-Shaped CNT@BNNS Covalent Heterojunction.

With the depletion of petroleum resources, the development of sustainable alternatives for plastic substitutes has grown in importance. It is urgently desirable yet challenging to design high-performance polyesters with extensive mechanical and prominent gas barrier properties. This work uses bio-based PBF polyester as a matrix, "leaf-shaped" carbon nanotube@boron nitride nano-sheet (CNT@BNNS) covalent hetero-junctions as functional fillers, to fabricate CNT@BNNS/PBF (denoted as CBNP) composite films through an "in-situ polymerizing and hot-pressing" strategy. The covalent CNT "stem" suppresses the re-stacking of BNNS "leaf", endowing hetero-structured CNT@BNNS illustrates superior stress transfer and physical barrier effect. The covalently hetero structure and high orientation degree of CNT@BNNS greatly improve the comprehensive performance of the CBNP composites, including excellent mechanical (strength of 76MPa, modulus of 2.3GPa, toughness of 85MJm-3, elongation at break of 193%) and gas barrier (O2 of 0.015 barrer, and H2O of 1.1 × 10-14g cm cm-2s-1Pa-1) properties that are much higher than for pure PBF or other-type polyesters, and most engineering plastics. Moreover, the CBNP composites also boast easy recyclability, overcoming the tradeoff between high performance and easy recycling of traditional plastics, which makes the polyester composite competitive as a plastic substitute.

Inorganic Semiconductor-Based Flexible UV Photodetector Arrays Achieved by Specific Flip-Chip Bonding.

In recent years, flexible UV photodetectors (PDs) with complex environmental adaptability and great wearability have attracted the attention of researchers worldwide. Wide bandgap inorganic semiconductor materials with excellent optoelectronic properties and mechanical stability are key functional materials for UV PD devices. However, the high temperature processing and inherent brittleness limit the further application of high-quality inorganic semiconductors in the field of flexible optoelectronics. In this work, we develop a specific flip-chip bonding fabrication technique that utilizes high-temperature treated inorganic semiconductor materials for high-performance flexible UV detection devices. Leveraging this technique, a 7 × 7 pixel flexible UV photodetector array (UV-FPDA) device based on a vertical architecture Mg-doped ZnO/NiO (Mg:ZnO/NiO) heterojunction transistor is built. The UV-FPDAs exhibit a high responsivity of 75.8 A/W and an outstanding detectivity of 8.5 × 1012 Jones. Besides, the UV-FPDAs also demonstrate excellent bending stability. Furthermore, the photoresponse characteristics of each pixel are trained and learned by an artificial neural network to achieve clear imaging of UV light information. Our results provide a new pathway for the application of inorganic semiconductors in the field of high-performance flexible UV photodetection.

Effect of cap layer and post growth on-site hydride passivation on the surface and interface quality of InAsP/InP hetero and QW structures

The performance of devices made from III-V compound semiconductors relies heavily on their surface and interface properties. The InAsP/InP material system is recently gaining interest due to its suitability for the next generation of long-haul classical and quantum communication applications. Researchers are studying how surface and interface properties affect the efficiency of the device and concludes that the epitaxial growth conditions responsible for creating surface and interface states require further improvement. To address this, we have studied the effect of the top (cap) layer and post-growth on-site hydride passivation on the properties of InAsP/InP hetero-structures grown using metal-organic vapor phase epitaxy technique. The flow rate and flux ratios of the hydrides significantly affect the surface reaction rates and gas-phase diffusion coefficients, which in turn impact the As↔P exchange mechanisms. Our findings suggest that post-growth on-site arsine passivation encourages the As↔P substitutions at the vicinity of the desorption sites of phosphorus, leading to the arsenic-rich surface of InAsP with the diffused hetero-interfaces. The activation energy for such As↔P exchange reaction mechanism is evaluated as ∼ (1.4 ± 0.3) eV. On the other hand, it has been observed that the thin cap layer of InP protects the surface of the InAsP epilayer and thereby preserving the sharp interface. Further, surface photovoltage and photoluminescence spectroscopy is employed to examine the role of the diffused and sharp interface of InAsP/InP hetero-structures in charge carrier transport, their redistribution and recombination process. Our analysis of the energy transitions occurring in the surface photovoltage and photoluminescence spectrum reveal that the energy band alignment and the subsequent charge carrier redistribution processes is influenced by the surface and interface states. These changes in the surface photovoltage phase spectra of InAsP/InP system also support the role of surface and interface states in the generation and separation of the charge carriers. The study provides insights into the effects of As↔P exchange on surface and interfacial quality, highlighting the implications for optoelectronic device development using InAsP/InP material system.

Low-cost deposition of tunable band gap Zn(O,S) as electron transport layer for crystalline silicon heterojunction solar cells

In recent years, the research on silicon heterojunction (HJT) solar cells based on dopant-free contacts has experienced rapid development. Zn(O,S) is a low work function n-type semiconductor compound with tunable band gap that can be used as the electron transport layer (ETL) in HJT solar cells. In our work, we choose Zn(O,S) as ETL and deposit it via the low-cost chemical bath deposition (CBD) method. Uniform and fast growth of Zn(O,S) films can be obtained by regulating the concentration of the complexing agent and the ratio of reactants to reduce the generation of impurities. To further achieve band matching with c-Si, the Zn(O,S) films are processed with air-annealing to modify the elemental ratios. The air-annealing lowers the interfacial electron transport barrier, which promotes charge separation and transport, thus reducing carrier recombination at the interface. Finally, the PCE of HJT solar cell based on CBD-Zn(O,S) ETL is close to 15 %, providing a new potential route for the development of low-cost HJT solar cells.

MoS2@Ti3C2Tx Heterostructure: A new negative electrode material for Li-Ion hybrid supercapacitors

Lithium-ion hybrid supercapacitors (LHSCs) demonstrate promising electrochemical performance, including long cyclic stability and a high-power density. However, their limited energy density has restricted the development towards commercialization. In this work, a novel heterostructure (HS) has been introduced based on molybdenum disulfide (MoS2) nanosheets (NSs) anchored on the surface of exfoliated layers of titanium carbide (Ti3C2Tx) MXenes. The prepared negative electrode material named as MoS2@Ti3C2Tx–HS holds substantial promise for advancing LHSCs to enhance energy density. The MoS2@Ti3C2Tx–HS demonstrates outstanding pseudocapacitive performance in a three-electrode system by achieving a capacitance of 1022.7 F g−1 at 1 A g−1. It exhibited a stable cyclic life (5,000 cycles) and retained 97.02 % of its initial capacitance. Theoretical calculations based on density functional theory (DFT) show impressive results to support the experimental work. The calculated density of states (DOS), band structures, adsorption energies (Eads), and diffusion energy demonstrate that MoS2@Ti3C2Tx–HS possesses excellent electronic and adsorption properties. The fabricated MoS2@Ti3C2Tx–HS//CP–LHSCs device shows a high capacitance of 153.75 F g−1 at 2 A g−1, with stable cyclic life (94.5 %) over 10,000 cycles. Furthermore, it shows a notable high energy density of 54.7 Wh kg−1 at a power density of 1,601.3 W kg−1. The prepared MoS2@Ti3C2Tx–HS electrode, with its synergistic combination, stands out as an auspicious material, showing remarkable electrochemical performance and paving the way for LHSCs.

Revealing the secrets of high performance lead-free CsSnCl3 based perovskite solar cell: A dive into DFT and SCAPS-1D numerical insights

In this study, a CsSnCl3/CBTS based hetero structure solar cell is proposed by incorporating effective ETLs like CBTS and HTLs built on C60. At first, electrical and optical properties of CsSnCl3 is determined with the help of DFT study. Those parameters are incorporated in SCAPS-1D to design the proposed solar cell. Numerical analysis demonstrates that heterostructures consisting of ITO/C60/CsSnCl3/CBTS/Au display remarkable photoconversion efficacy. In addition, the impact of CsSnCl3 thickness, series resistance, light conversion efficiency, also working temperature is investigated additionally to optimize the cell performance. Furthermore, the composed impacts of thickness of absorber and ETL, defect density, electron affinity (eV), absorption thickness, and doping are also explored. The SCAPS-1D simulation results, which show an ideal open-circuit voltage of 1.18 V, a short-circuit current density of 22.22 mA/cm2, a fill factor of 87 %, and an overall efficiency of 20.5 %, are in good agreement with both simulated and experimental data published in the literature. This thorough simulation analysis provides insightful information and identifies a viable path for future CsSnCl3-based solar cell development.

The robustness waterproof ionogel based on the phase separation to form soft hard heterostructures and the interaction of cation-π realizes underwater adhesion and sensing

Flexible ionic conductors hold significant promise for advancing the field of soft ion electronics in the future. However, the creation of flexible conductors that possess mechanical robustness, underwater adhesion and underwater motion monitoring remains a challenge. Drawing inspiration from the multiphase hetero structure found in biological connective tissues, such as high modulus fibers and low modulus water-rich matrices, this article proposes a one-pot polymerization in-situ design strategy to create a hydrophobic ionogel with a hetero structure of soft and hard domains. The mechanical robustness, elasticity, and toughness of the ionogel are achieved through a synergistic combination of a strong skeleton in the hard domain and an elastic matrix in the soft domain. Additionally,hydrophobic aromatic rings and quaternary ammonium cation simulated cation-π interactions in mussel foot silk protein. Upon contact with water, the hydrophobic clusters quickly aggregate, facilitating the expulsion of interfacial water and exposing salicylic acid groups and quaternary ammonium cationic groups, leading to outstanding underwater adhesion between the ionogel and various substrates. The resulting hydrophobic ionogel can be utilized in underwater wearable electronic devices for monitoring human movement and physiological information, underwater repair monitoring, and intelligent soft robotics, demonstrating its vast potential in the field of underwater sensors.

High Selectivity MEMS C2H2 Sensor for Transformer Fault Characteristic Gas Detection**

AbstractAcetylene (C2H2), as an important characteristic gas in transformer fault diagnosis, should be accurately detected and effectively distinguished from other dissolved gases (H2, CH4, C2H6, C2H4, CO, CO2), which is crucial to determine whether the fault occurs and the fault type, but also faces challenges now. The rational design and employment of rare earth and noble metals are expected to address this issue. In this work, SnO2‐3 at% Sm2O3‐1 at% PdO based MEMS gas sensor was prepared to achieve high performance detection of C2H2 which has a response value of 56 to 50 ppm C2H2, response/recovery time of 2 s/136 s, lower detection limit of 1 ppm, power consumption of 15.5 mW, and weak cross sensitivity to other transformer fault characteristic gases. Lewis acids and bases theory was used to explain the reason why rare earth Sm is a benefit element to improve selectivity to C2H2. The formation of oxygen vacancies and hetero junctions was used to explain the increased sensitivity of the material. This study proved the feasibility of rare earth and noble metals as potential additives to enable advanced gas‐sensitive materials for highly selective transformer fault characteristic gas C2H2 detection.

Influence of copper on zinc oxide films and solar cell performance

Copper doped Zinc oxide and (n-ZnO / p-Si and n-ZnO: Cu / p-Si) thin films thru thickness (400±20) nm were deposited by thermal evaporation technique onto two substrates. The influence of different Cu percentages (1%,3% and 5%) on ZnO thin film besides hetero junction (ZnO / Si) characteristics were investigated, with X-ray diffractions examination supports ZnO films were poly crystal then hexagonal structural per crystallite size increase from (22.34 to 28.09) nm with increasing Cu ratio. The optical properties display exceptional optically absorptive for 5% Cu dopant with reduced for optically gaps since 3.1 toward 2.7 eV. Hall Effect measurements presented with all films prepared pure and doped have n-types conductive, with a maximum carriers concentrate of 3.9×1016 (cm-3 ) besides lower resistivity of 59.6 (Ω.cm) for films doped with 5% (Cu). The current- voltage (I-V) characteristics of heterojunction below illumination by incident power density (100 mW/cm2 ) showed that heterojunction (n-ZnO: 5%Cu / p-Si) has maximum efficiency (η =3.074 %).