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Hybrid microwave annealing for fabrication of more efficient semiconductor photoanodes for solar water splitting
摘要： Hybrid microwave annealing (HMA) is proposed as an alternative to conventional thermal annealing (CTA) in a furnace to fabricate efficient semiconductor photoelectrodes for solar water splitting. Thus the effects of HMA are investigated in comparison with CTA using spinel zinc ferrite as an example. The ZnFe2O4 photoanodes fabricated by HMA with a graphite susceptor provide less defective surface, better structural ordering and smaller feature size than photoanodes prepared by CTA. Besides, HMA does not impair conductivity of the F:SnO2 glass substrate. All these positive factors of HMA leads to ~4 times higher photocurrents at 1.23 VRHE and lowered onset potential by ~100 mV under 1-sun irradiation of an optimized ZnFe2O4 photoanode relative to that fabricated by CTA. The HMA could be an effective generic method to fabricate efficient photoelectrodes based on refractory semiconductors replacing incumbent CTA.
关键词： Conventional thermal annealing,ZnFe2O4,Hybrid microwave annealing,Photoelectrochemical water splitting
更新于2025-09-10 09:29:36
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The effects of rapid thermal annealing and microwave annealing on the electrical properties of ZrO2 metal-insulator-metal capacitors
摘要： The effects of different rapid thermal annealing (RTA) and microwave annealing (MWA) on the electrical behaviors of ZrO2 metal-insulator-metal (MIM) capacitors were studied in detail. The maximum capacitance density was achieved at 1400 W for MWA, i.e. ~29.29 fF/μm2 increased by ~40% compared with that of the un-annealed capacitors. For the capacitors under RTA at 370 oC, equivalent to the ambient of the MWA at 1400 W, the capacitance density is ~28.04 fF/μm2. Moreover, the leakage current density of ZrO2 MIM capacitors for MWA at 1400 W and RTA at 370 oC are determined to be about 3.55×10-7 A/cm2 and 1.88×10-6 A/cm2 at the applied voltage of -1.5 V, respectively. Finally, the possible mechanisms of the improved electrical properties of ZrO2 MIM capacitors through MWA were proposed.
关键词： ZrO2,Rapid thermal annealing,Metal-insulator-metal Capacitors,Microwave annealing
更新于2025-09-10 09:29:36
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Transparent p-Cu0.66Cr1.33O2/n-ZnO heterojunction prepared in a five-step scalable process
摘要： Transparent and electrical conducting p-type off-stoichiometric copper–chromium oxide thin films were used to build p-Cu0.66Cr1.33O2/n-ZnO heterojunctions. The junctions were fabricated in a novel and simple five step process including metal organic chemical vapour deposition, atomic layer deposition, chemical wet etching, and optical lithography. One last step of thermal annealing, with varying temperatures of 650 and 700 °C, is added in order to tune the electrical properties of delafossite and consequently the electrical features of p–n junctions. This work was developed to address the lack of transparent and industrially scalable rectifying p–n junctions that can open multiple application paths in transparent electronics. A competitive ideality factor η of 6.6 and a transmittance in the visible range of 50% were achieved. An understanding of the electronic response of junctions is presented herein as well as a deepening comprehension of the physical properties of materials, with the bands alignment and the Fermi level tuning.
关键词： Atomic layer deposition,Optical lithography,Thermal annealing,Delafossite,Metal organic chemical vapour deposition,p-Cu0.66Cr1.33O2/n-ZnO heterojunctions,Transparent electronics,Chemical wet etching,Fermi level tuning
更新于2025-09-10 09:29:36
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Phase-separated structures of random methacrylate copolymers with pendant POSS moieties
摘要： The phase separation of random methacrylate copolymers with the pendant polyhedral oligomeric silsesquioxanes (POSS) moieties was studied. For the random copolymers of the phenyl-substituted POSS methacrylate (PhPOSSMA) and butyl methacrylate (BMA), the layer-like phase-separated structures were obtained from the copolymers with over circa 20 wt % of PhPOSSMA after thermal annealing in the bulk. The copolymers with larger PhPOSSMA content over 40 wt % showed periodic phase-separated structure with the periodic length ranging from 9.0 to 5.1 nm depending on the composition. The phase separation did not occur by solvent annealing in the bulk. On the other hand, no phase-separated structure was formed from the random copolymer with circa 50 wt % of isobutyl-substituted POSSMA (i-BuPOSSMA) and BMA after thermal annealing. In addition, the phase separation did not occur for both of the random copolymers of PhPOSSMA and i-BuPOSSMA with methyl methacrylate. The resulting phase-separated structures were well characterized by using wide-angle X-ray scattering, small-angle X-ray scattering, and transmission electron microscopy image.
关键词： random copolymer,POSS,phase-separated structure,thermal annealing,poly(methacrylate)
更新于2025-09-10 09:29:36
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Tailoring the Structural and Optical Parameters of Eu3+:CeO2-SiO2 Nanopowder Via Thermal Treatment
摘要： Nanocrystalline Eu3+:CeO2-SiO2 powder samples were prepared by sol-gel technique. This technique is suitable for large-scale production and it is also a cost effective process. The prepared samples were annealed at different temperatures which were characterized by many complementary techniques. The formation of cubic fluorite structure of CeO2 nanocrystal with a uniform distribution was confirmed by x-ray diffraction (XRD) and transmission electron microscopy (TEM). The average nanocrystalline size has been calculated as 3, 7 and 15 nm using Debye-Scherrer formula for different annealed samples. The calculated nanocrystalline sizes were compared with W-H plot and TEM histograms. It was investigated that FWHM of diffraction peaks decreases with increase in temperature results in increase nanocrystalline size. The FTIR spectroscopy provides the valuable information and identification of different chemical group/bonds present in the prepared samples. It is found that if we fixed the dopant concentration, then particle size, morphology and band gap energy of prepared nanopowder can be tailored by applying the annealing conditions. Comparative studies of absorption spectra and corresponding band gap energies have been done and a red shift has been observed in absorption spectra with thermal treatment. The shift of the optical absorption edge of prepared nanopowder towards lower energies increases its utilization in the visible region specially photocatalytic activity.
关键词： Thermal annealing,Absorption spectra,Structural properties,Nanopowder,Band gap energy
更新于2025-09-10 09:29:36
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Driving chemical interactions at graphene-germanium van der Waals interfaces via thermal annealing
摘要： Despite its extraordinary charge carrier mobility, the lack of an electronic bandgap in graphene limits its utilization in electronic devices. To overcome this issue, researchers have attempted to chemically modify the pristine graphene lattice in order to engineer its electronic bandstructure. While significant progress has been achieved, aggressive chemistries are often employed which are difficult to pattern and control. In an effort to overcome this issue, here we utilize the well-defined van der Waals interface between crystalline Ge(110) and epitaxial graphene to template covalent chemistry. In particular, by annealing atomically pristine graphene-germanium interfaces synthesized by chemical vapor deposition under ultra-high vacuum conditions, chemical bonding is driven between the germanium surface and the graphene lattice. The resulting bonds act as charge scattering centers that are identified by scanning tunneling microscopy. The generation of atomic-scale defects is independently confirmed by Raman spectroscopy, revealing significant densities within the graphene lattice. The resulting chemically modified graphene has the potential to impact next-generation nanoelectronic applications.
关键词： graphene,van der Waals interfaces,germanium,Raman spectroscopy,chemical bonding,scanning tunneling microscopy,thermal annealing
更新于2025-09-10 09:29:36
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Broadband UV-assisted thermal annealing of low- <i>k</i> silicon carbonitride films using a C-rich silazane precursor
摘要： Low-k dielectric silicon carbonitride (SiCxNy) films are deposited by plasma-enhanced chemical vapor deposition using a carbon-rich silazane precursor, N-methyl-aza-2,2,4-trimethylsilacyclopentane (SiC7NH17), at 100 °C. The post-treatments of SiCxNy films are carried out by thermal annealing and a broadband UV-assisted thermal annealing (UV-annealing) at 400 °C for 5 min. Compared to the thermal annealing treatment, UV-annealing can improve both dielectric and mechanical properties of low-k SiCxNy films. Under thermal annealing, SiCxNy films show great thermal stability, but little structural change. In contrast, upon UV-annealing, most of the Si–H and N–H bonds are broken up, which induces more Si–N cross-linking and converts Si–C matrix into Si–N matrix. The ethylene bridges in Si–(CH2)2–Si also remain intact, but the unbridged hydrocarbons in Si–(CH2)2–N and Si–CH2–CH3 bonds decompose completely during the UV-annealing process. These account for the reduced dielectric constant to k = 3.2 from 3.6 and a 21% enhancement of Young’s modulus to 7.4 GPa in the SiCxNy films after UV-annealing. Broadband UV-annealing shows promise as a post-treatment method for enhancing the properties of low-k dielectric barrier, SiCxNy films.
关键词： low-k dielectric,silicon carbonitride,UV-assisted thermal annealing,plasma-enhanced chemical vapor deposition,mechanical properties
更新于2025-09-10 09:29:36
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Chemical Vapor Deposited Vanadium Pentoxide Nanosheets with Highly Stable and Low Switching Voltages for Effective Selector Devices
摘要： Recently, attempts to overcome the physical limits of memory devices have led to the development of promising materials and architectures for next-generation memory technology. The selector device is one of the essential ingredients of high-density stacked memory systems. However, complicated constituent deposition conditions and thermal degradation are problematic, even with effective selector device materials. Herein, we demonstrate the highly stable and low threshold voltages of vanadium pentoxide (V2O5) nanosheets synthesized by facile chemical vapor deposition, which have not been previously reported on the threshold switching properties. The electrons occupying trap sites in poly-crystalline V2O5 nanosheet contribute to the perfectly symmetric threshold switching feature at the bias polarity and low threshold voltages in V2O5, confirmed by high-resolution transmission electron microscopy measurements. Furthermore, we find an additional PdO interlayer in V2O5 nanodevices connected with a Pd/Au electrode after thermal annealing treatment. The PdO interlayer decreases the threshold voltages, and the Ion/Ioff ratio increases because of the increased trap density of V2O5. These studies provide insight into V2O5 switching characteristics, which can support low power consumption in non-volatile memory devices.
关键词： nanosheets,selector devices,vanadium pentoxide,threshold switching,thermal annealing treatment
更新于2025-09-10 09:29:36
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The Variation of Crystalline Structure Induced by Gas Dilution and Thermal Annealing in Silicon Layers Deposited by PECVD Technique
摘要： We prepared hydrogenated thick silicon film by plasma enhanced chemical vapor deposition (PECVD) method using SiH4 and H2 gas mixture and we investigated the effect of the hydrogen dilution ratio defined as R = H2/SiH4 on the as-deposited and annealed films. With increase in hydrogen dilution ratio, amorphous to microcrystalline transition has been observed. The crystallization has been confirmed from Raman spectroscopy, UV reflectance, low angle X-ray diffraction (XRD), spectroscopic ellipsometry and atomic force microscopy (AFM) analysis. Tauc band gap shows a decreasing trend with increasing H2 dilution of silane. It decreases from 1.8 to 1.57 eV. It has been concluded that H2 dilution of silane in PECVD enhances the crystallinity of the film and affects its optical and structural properties.
关键词： Silicon nanocrystallites,Hydrogen dilution,Thermal annealing,PECVD,Crystallization
更新于2025-09-09 09:28:46
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Gallium Oxide || Ohmic contacts to gallium oxide
摘要： The deposition of a metal onto a semiconductor surface to provide low contact resistance, high-reliability electrical contacts without adversely affecting the device during the metallization process is one of the most important challenges in device fabrication. Consequently, a fundamental understanding of how contacts work is essential for successful device manufacturing and commercialization. The physics of carrier transport across the metal-semiconductor junction renders metal contacts either rectifying (a.k.a. Schottky) or nonrectifying. A nonrectifying contact whose relationship between current and voltage has a low interfacial contact resistance Rc, and is preferably linear, is referred to as an Ohmic contact. Achieving low contact resistance Rc (Ω mm) or contact resistivity ρc (Ω cm2) has required a great amount of investigation for every relevant semiconductor material in the past. Typically, the successful formation of an Ohmic contact has relied on three constituent requirements: highly or degenerately doped semiconductor, choice of metallization, and thermal annealing. In the case of silicon, for instance, diffusion processes have been the topic of much early work but ultimately the control and reproducibility of ion implantation have rendered it an industry standard. For compound semiconductor heterostructure devices based on GaAs or GaN, the presence of a two-dimensional electron gas (2DEG) has necessitated a multilayer metallization deposition and annealing scheme, the details of which took many years to optimize. Particularly in the case of III-nitride high electron mobility transistors (HEMTs), Ohmic contacts were relatively easy to make on heteroepitaxal GaN due to its high dislocation density as the barrier height was reduced through defect-assisted formation of metal-nitride alloys during the anneal. Subsequent breakthroughs in GaN crystal growth, however, resulted in several orders of magnitude lower dislocation density homoepitaxial GaN, and naturally the contact resistance obtained under identical process conditions was higher [1]. Regrowth techniques to provide n+-doped GaN have become commonplace as a result.
关键词： thermal annealing,semiconductor,metallization,gallium oxide,contact resistance,Ohmic contacts
更新于2025-09-09 09:28:46