Papers by Keyword: Heterojunction

Abstract: This study investigates the synergistic potential of a novel heterojunction photocatalyst for methyl orange degradation. The photocatalyst comprises iron tungstate (FeWO₄) and graphitic carbon nitride (g-C₃N₄), engineered to exploit the distinct properties of each component for enhanced photocatalytic activity. The research systematically evaluates the performance of the synthesized FeWO₄/g-C₃N₄ composite in degrading methyl orange, with an emphasis on optimizing catalytic efficiency. The photocatalyst was characterized using advanced techniques, including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) to elucidate its structural and morphological properties. Key parameters such as loading concentrations were optimized to assess their influence on the photodegradation efficiency. Among tested compositions, 1.0 wt% FeWO₄/g-C₃N₄ achieved the highest degradation efficiency of MO at 78.04% within 180 minutes under UV irradiation. The heterojunction structure promoted effective charge separation, and further enhanced visible-light response. These results demonstrate the catalyst’s potential for sustainable water purification applications.

Abstract: The detection of ethanol (C₂H₆O), a toxic and hazardous gas, is important for environmental monitoring and industrial safety. This study synthesised a SnO₂-doped NiO (SnO₂-NiO) heterojunction via a hydrothermal method for high-performance ethanol gas sensing applications. The thick films of synthesized materials were developed by using the screen printing technique. In this work, SnO₂ is used as a dopant while NiO is base material. The concentration of SnO₂ is varied from 0.1 N, 0.3 N, 0.5 N, to 0.7 N in the NiO during synthesis. The nanostructure leverages the superior gas-sensing properties of the n-type semiconducting behavior of SnO₂ and the p-type semiconducting behavior of NiO, forming an efficient p-n heterojunction interface. The synthesized material was characterized using X-ray diffraction (XRD), TEM (Transmission Electron Microscopy), field emission scanning electron microscopy (FESEM), and energy dispersive spectroscopy (EDS) to confirm the formation of the heterojunction and analyze its morphology and elemental composition. Gas sensing examinations demonstrated that the SnO₂-doped NiO heterojunction exhibited excellent selectivity (86.74%) and sensitivity towards ethanol at 150°C operating temperatures, with rapid response and recovery times. The enhanced gas-sensing performance is attributed to the synergistic effects between SnO₂ and NiO, which promote electron transfer and improve the interaction with ethanol gas molecules. This work highlights the potential of SnO₂-doped NiO heterojunction in developing highly sensitive and selective ethanol gas sensors for environmental and industrial applications.

Abstract: In this study, ZnO-TiO₂ nanocomposites with varying molar ratios were synthesized using a hydrothermal method and characterized for H₂S gas sensing applications. Thick films of the nanocomposites were fabricated using a screen-printing technique, and their gas sensing performance was evaluated at different operating temperatures. The diffraction peaks of ZnO and TiO₂ are hexagonal (rutile), and tetragonal (anatase) phase, respectively. The crystallite sizes were determined to be 37.34 nm for 1M ZnO : 1M TiO₂ composition, and 45.17 nm, 44.03 nm, 41.22 nm, 36.14 nm, and 36.65 nm for the (1M : 9M, 3M : 7M, 7M : 3M, 9M : 1M, and 0.1M CuCl₂-doped in 1M ZnO : 1M TiO₂) compositions, respectively. SEM and EDAX analyses revealed formation of heterogeneous structure with well-distributed nanospheres and nanorods. The I-V characteristics of ZnO-TiO₂ thick films show a proportional but slightly non-linear response to voltage, indicating a mix of ohmic and non-ohmic conduction. The average thickness of the thick film of 1M ZnO : 1M TiO₂ sample is 29 (µM). The gas sensing performance was evaluated at different operating temperatures and among the compositions studied, the 7M ZnO : 3M TiO₂ thick film exhibited superior sensitivity, selectivity, and response to 286 ppm H₂S gas at 40°C. These findings demonstrate the potential of ZnO-TiO₂ nanocomposites as highly selective and low-temperature H₂S sensor for industrial and environmental monitoring applications.

Abstract: The heterojunction structure Cd(OH)₂/Bi₁₀Cd₃O₂₀ was successfully constructed through a straightforward hydrothermal method. The product was characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), high resolution transmission electron microscope (HRTEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), Diffuse reflectance spectrum (DRS), Raman analysis, photocurrent and electrochemical impedance spectroscopy (EIS) measurements. SEM, HRTEM and Raman analysis confirmed that the nanorod Bi₁₀Cd₃O₂₀ was effectively stacked on the surface of the hexagonal microblock Cd(OH)₂, forming the heterojunction composite. This composite demonstrated exceptional photocatalytic performance in the degradation of azo dye pollutants, with a degradation rate for Rhodamine B reaching 98% under optimal synthesis conditions. A plausible photocatalytic mechanism for the heterojunction composite, based on a type I n-n heterojunction, was also proposed. The heterostructure significantly facilitates the migration and separation of charge carriers, thereby enhancing the photoactivity and stability.

Abstract: The antibiotic pollutant treatment in wastewater using conventional method remains a challenge. One of the most fluoroquinolone antibiotics family used by human and animal cure is ciprofloxacin (CIP). CIP has exhibited as a recalcitrant compound in nature with concentration from ng to mg. To overcome this issue, recent technologies have applied such as photocatalysis technology for water decontamination. Furthermore, photocatalyst materials that used in this research were zinc ferrite and graphitic carbon nitride. A simple hydrothermal-coprecipitation method has succeed to synthesis zinc ferrite. While, unexfoliated graphitic carbon nitride (ZFO@ue-CN) was synthesized by calcination at 550 °C for 4 h under air condition. A heterostructure approach combining zinc ferrite and unexfoliated graphitic carbon nitride (ZFO@ue-CN) has been investigated as a potential solution. In this study, a ZFO@ue-CN was constructed by calcination method under atmosphere condition at 400 °C for 2 h. The ZFO@ue-CN has been characterized involving structural, morphological, and optical. Furthermore, ZFO@ue-CN exhibited excellent degradation performance with over 88% removal of ciprofloxacin. The heterojunction formation of ZFO@ue-CN nanocomposite provide more efficient electron transfer compared to single material. Combination between metal oxide@ue-CN can open up the new platform for simple material preparation, nevertheless it can keep the photodegradation performance. This result also emphasizes that the ZFO@ue-CN nanocomposites has prominent application for wastewater treatment.

Abstract: Mixed oxide of titanium dioxide was synthesized by adding SnO₂ and CeO₂ through a precipitation method for the degradation of methylene blue (MB) under visible light. The as-prepared was dried and calcined at various temperatures, i.e. 450-750 °C. The calcined products were characterized by XRD, DRUV, and FTIR. The effect of calcination temperature was studied on the photodegradation of MB under visible light. The photocatalytic activity showed that calcined photocatalytic at 650 °C shows the lowest bandgap energy and the highest photocatalytic activity in the decomposition of methylene blue under visible light.

Abstract: Gas sensors have been widely implemented to solve concerns of air pollution, monitor human health, and crop yields. Because of its high sensitivity, quick response time, and short recovery time, metal oxide semiconductor (MOS) gas sensors have become a significant topic of research in the field of gas sensing. In the recent decade, many researchers are work on the different types of pure and doped MOS for improve gas sensor response. The present research work deals with the fabrication of p-n heterojunction thin films on alumina substrate by using thermal evaporation technique for reducing gas sensing application. In the current research work, ZnO is used as a functional material and MgO as a dopant. The structural, electrical, and gas sensing properties of fabricated p-n (CuO-ZnO) heterojunction thin films were studied. The resistivity of p-n heterojunction thin films was found to be 23.461Ω/m. The found to be negative to p-n heterojunction thin films. The morphological, elemental and structural characterization of fabricated CuO-ZnO heterojunction thin films were analyzed by using , EDAX and XRD standard tools respectively. By using Scherer’s formula the crystallite size of CuO-ZnO heterojunction thin films was found as 36.83 nm. The fabricated CuO-ZnO heterojunction thin films were exposed to reducing gases such as Liquefied petroleum (LPG), Ammonia (NH₃), Ethanol (C₂H₅OH), and Dichlorofluoromethane (R12) to determine gas response and selectivity. Fabricated CuO-ZnO heterojunction thin films shows maximum response to LPG gas as compare to other gases. The maximum sensitivity has to be found 89.23% to LPG gas of concentration 300 ppm. Fabricated MgO-ZnO thin films also show fast response and recovery time in seconds.

Abstract: In the present work we have reported the realization and characterization of CH₃NH₃PbI₃/c-Si heterojunction. It was achieved by deposing CH₃NH₃PbI₃ perovskite film on (P) doped single crystalline Silicon (c-Si) substrate by spin coating. The structural, optical and electrical properties of perovskite film were investigated. The electric characterization of the realized device was achieved through I-V and G-f measurements. The recorded I-V characteristic exhibits a rectifier behavior. This curve was used also to determine diode parameters; the ideality factor, the saturation current, the series resistance and the potential barrier. However, the conductance method was used to assess the interface state N_ss via (G/ω) versus angular frequency ω curve. The results were used to justify the large values of the ideality factor and the series resistance.

Abstract: Broadband ultraviolet (BUV) photodetectors are widely used in military and civil fields. A high performance BUV photodetector based on graphene/β-Ga₂O₃/GaN heterojunction is proposed and realized by semiconductor micro-fabrication techniques in this paper. The β-Ga₂O₃ and GaN films are grown by metal organic chemical vapor deposition (MOCVD), and the graphene is also used as a transparent electrode. The device exhibits a broad response band from 230 nm to 368 nm with responsivity exceeding 0.4A/W at -5 V bias voltage and a peak responsivity of 0.53 A/W at 256 nm. These performances can be attributed to the internal gain mechanism of graphene/β-Ga₂O₃/GaN heterojunction and the optical properties of graphene. Our work provides an efficient method to realize a high-performance BUV photodetector for photoelectric applications.

Abstract: In this work, we have analyzed the digital and analog performance for InGaAs/InP heterojunction Gate all around MOS structure. A detailed study on the impact of Barrier thickness on different analog and digital performance for an InGaAs/InP hetero structure GAA MOSFET is carried out by using TCAD device simulation. The electrical parameters such as surface potential, electric field, transfer characteristics, output characteristics, transconductance and output conductance is carried out and analyzed by varying the barrier thickness from 1 nm to 4 nm. Based on the simulation results it is investigated that the effect of the all electrical parameters in the nanoscale devices. It has been seen from the presented results that the influence of barrier thickness variation gives the notable improvement in drain current. The impact of InGaAs/InP hetero structure and barrier thickness variation claims GAA MOSFET as a promising candidate for VLSI applications. Keywords: Heterojunction, InGaAs/InP, TCAD, Analog parameters.