Influence Of Fabrication Process Research Articles

Influence of Fabrication Processes on Transport Properties of Superconducting Niobium Nitride Nanowires

Fabrication of niobium nitride (NbN) superconducting nanowires based on focused ion beam (FIB) milling and electron beam lithography (EBL) is presented. The NbN films were deposited using reactive magnetron sputtering. Argon-to-nitrogen ratio turned out to be a crucial factor in synthesizing high quality superconducting NbN. Critical temperatures (T c ) of around 15.5 K were measured for films with a thickness of around 10 nm. Zero-field-cooled magnetization was measured to optimize the superconducting properties of ultra thin NbN films. The transport behaviour was studied using conventional resistance vs temperature and current-voltage characteristics down to 2 K. Effect of gallium contamination on superconducting properties has been discussed. Whereas the various processing steps of standard EBL route do not have any significant impact on the superconducting transition temperature as well as on the transition width of nanowires, there is significant degradation of superconducting properties of nanowires prepared using FIB. This has been attributed to gallium ion implantation across the superconducting channel. Although the effect of gallium implantation may have technological limitations in designing fascinating single photon detector architectures, it provides some interesting low-dimensional superconducting properties.

Ablation and spectroscopic characteristics of thin CuIn1-xGaxSe2 solar cell films fabricated by co-evaporation and co-sputtering processes

The influence of fabrication processes on the LIBS (Laser Induced Breakdown Spectroscopy) spectra of major and minor chemical constituents in CuIn1-xGaxSe2 (CIGS) absorber films produced by co-sputtering and co-evaporation techniques on Mo-coated soda lime glass (SLG) is reported. It was found that the ablation rate per pulse of CIGS layers fabricated by the co-sputtering technique is higher than those fabricated by the co-evaporation technique, resulting in higher LIBS signal intensities of the constituent elements. The examination of surface morphology of irradiated surfaces and changes in LIBS signal intensities revealed evidences of elemental fractionation for the CIGS films fabricated by co-sputtering technique but not for those by co-evaporation technique. From x-ray diffraction measurements, it was confirmed that the differences in the ablation and spectroscopic characteristics of the two different types of CIGS absorber films were contributed to the differences in crystalline properties. Furthermore, it was demonstrated that LIBS can effectively determine a depth profile of sodium concentration in CIGS thin films, diffused from SLG.

Effective fabrication method of 3D ceramic photonic crystals with diamond structure

PurposeThe purpose of this paper is to present a novel and effective fabricating method of 3D ceramic photonic crystals with diamond structure.Design/methodology/approachThe reverse diamond‐structure resin molds are fabricated by stereolithography (SL), then ceramic slurry is prepared and injected into the molds under vacuum condition. Subsequently, ceramic photonic crystals are obtained after vacuum freeze‐drying and sintering.FindingsThe combination of SL, gel‐casting and freeze‐drying could be used to fabricate the 3D ceramic photonic crystals with diamond structure which have intact structure and minimal shrinkage. The samples have been tested and the experimental results indicate that their band gap is in the range of 10.14‐12.20 GHz, consistent with the simulation results.Research limitations/implicationsThe influence of fabrication process on the photonic band gap needs further study.Originality/valueThis paper presents a novel fabricating method of 3D diamond‐structure ceramic photonic crystals based on SL, gel‐casting and freeze‐drying. The method fabricates complex ceramic photonic crystals with high accuracy and helps further research in this field.

Influence of Fabrication Process on Magnetic Properties of Co-Finemet Nanocrystalline Powder Core

Abstract. Rapidly quenched ribbons of Fe63.5Co10Si13.5B9Cu1Nb3alloy were annealed at 550°C in a vacuum for 1h and milled to powders. Cold-pressed nanocrystalline powder cores were fabricated using 1-5wt.% of epoxy E-44 as the binder and 1wt.% of Zn-stearate for lubrication under the pressure 155-200KN. The microstructure and morphology of powders were characterized with XRD and SEM. The effective permeability (μe) and quality factor (Q) were tested by using LCR HiTESTER 3532-50 in the range of 1–5000 kHz. The results show that the μe of the powder cores increased with the particle size. Powder cores with 2wt.% binder exhibited higher μe, but lower Q compared with samples with 3wt.% binder. Increase of the forming pressure helps improve μe, but the excessive stress caused by the forming pressure had a negative effect for μe.

The influence of fabrication process on top-gate thin-film transistors

Amorphous indium zinc oxide (a-IZO) thin-film transistors (TFTs) with bottom- and top-gate structures were fabricated at room temperature by direct current (DC) magnetron sputter in this research. High dielectric constant (κ) hafnium oxide (HfO 2) films and a-IZO were deposited for the gate insulator and the semiconducting channel under a mixture of ambient argon and oxygen gas, respectively. The bottom-gate TFTs showed good TFT characteristics, but the top-gate TFTs did not display the same characteristics as the bottom-gate TFTs despite undergoing the same process of sputtering with identical conditions. The electrical characteristics of the top-gate a-IZO TFTs exhibited strong relationships with sputtering power as gate dielectric layer deposition in this study. The ion bombardment and incorporation of sputtering ions damaged the interface between the active layer and the gate insulator in top-gate TFTs. Hence, the sputtering power was reduced to decrease damage while depositing HfO 2 films. When using 50 W DC magnetron sputtering, the top-gate a-IZO TFTs showed the following results: a saturation mobility of 5.62 cm 2/V-s; an on/off current ratio of 1 × 10 5; a sub-threshold swing (SS) of 0.64 V/decade; and a threshold voltage ( V th ) of 2.86 V.

Low-temperature sintering and microwave dielectric properties of TiO2-based LTCC materials

Temperature stable high-K LTCC material was prepared. The influence of fabrication process on the crystalline phases, microstructures and microwave dielectric properties of TiO2-Bi2O3-CuO ceramics were investigated. The crystalline phases and microstructures of TiO2-Bi2O3-CuO ceramics were investigated by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. It was found that rutile TiO2 phase and Bi2Ti4O11 phase co-existed in the TiO2-Bi2O3-CuO ceramics. Separate TiO2 grains and Bi2Ti4O11 grains distributed uniformly in the ceramic matrix. The composition 0.92TiO2-0.08Bi2Ti4O11 with 2 wt% CuO addition that was sintered at 900 °C for 2 h showed high dielectric constant (er ~ 81), high quality factor (Q × f ~ 3,500 GHz) and near zero temperature coefficient of resonant frequency (τf ~ −5.1 ppm/°C), meanwhile the compatibility test showed that it could co-fire with silver electrode. The processing-microstructure-property interrelationship was also studied.

Influence of fabrication process on the final properties of natural-rubber latex tubes for vascular prosthesis

We report a process of fabrication of latex tubes using the dip-coating technique. We investigated centrifuged latex, with different original viscosities, extracted from the Hevea brasiliensis. The influence of the main deposition parameters (dip-coating velocity, mold material, mold diameter and number of coatings) and post-deposition drying process parameters (temperature and time) on the properties of the final samples are investigated and discussed. Additional investigation about the elastic behavior of the tubes is presented for strain values up to rupture. The rupture occurred at 120 mm for tubes 15 mm-long, which represents an elongation of 800%. The tubes presented two distinct elastic mechanisms, with the most elastic one being observed below an elongation of about 500%. During a cycled strain experiment with strain values below the rupture point, a hysteretic-like curve was observed, which was related to the uncurling and recurling of the polymeric chains.

Fabrication of Spin-Coated Optical Waveguides for Optically Interconnected LSI and Influence of Fabrication Process on Underlying Metal–Oxide–Semiconductor Capacitors

A microscopic optical waveguide fabrication technique on silicon substrates at low temperatures using a fluorinated polyimide (FPI) is developed for application in an optically interconnected LSI. Propagation loss decreases to about 1.0 dB/cm in the miniaturized FPI waveguide with a core size of 1.5×10 µm2 made on a thermal oxide film and to about 4.8 dB/cm in a waveguide with a core size of 1×10 µm2 made on spin-on-glass. Furthermore, the FPI waveguides are also fabricated on metal–oxide–semiconductor (MOS) capacitors, and the influence of the waveguide fabrication including a plasma etching process on the underlying MOS capacitors is evaluated by examining the time-dependent dielectric breakdown characteristics. It is observed that plasma damage in the dry etching process may not be so large, but the damage at the spin-coating step for spin-on-glass for clad layer formation on a MOS capacitor is relatively large in the FPI waveguide fabrication process.

Investigating the influence of fabrication process and crystal orientation on shear strength of silicon microcomponents

A summary of the influence of microfabrication processes (wet and dry etching) and crystal orientation on the effective shear strength of microridges is addressed in this paper. Test results indicate that both crystal orientation and geometry plays an important role in determining the strength. The largest shear strengths obtained were for triangular and rectangular ridges fabricated with wet etching and deep RIE respectively. Both of these structures had similar crystal orientations. These strength values were approximately 3.5 times larger than the lowest strengths measured for wet etching structures. Using Chlorine RIE, we were able to demonstrate the influence of crystal orientation on strength, with microridges of {110} sidewall made on a (100) wafer the largest. For wet etching, we found that the strength was concentration dependent. For example, a 45% KOH fabricated structure produced strength values 65% higher than 30% KOH fabricated ones (note crystal orientation the same). This was attributed to a geometric effect, that is the 45% KOH solution had a “V” shaped bottom while the 30% KOH had a flat bottom. EDP and TMAH values had similar strengths to the 30% KOH solution (note similar crystal orientation). Therefore, microcomponent strength is strongly dependent upon fabrication process as well as crystal orientation.

Influence of fabrication process on the performance of light-emitting diodes

We have investigated the influence of device fabrication process on the performance of poly (p-phenylene vinylene) (PPV) and poly (N-vinyl carbazole) (PVK) blended with triphenylamine (TPA) (PVK:TPA)-based light-emitting diodes by constructing various devices with different structures and treated under different conditions. Thermal treatments make modifications to the contacts, affect the electrical properties of the polymer, change the rectification ratio by orders of magnitude, and affect the efficiency of the devices. Partially converted PPV improved the efficiency due to short conjugated length, but results in the stability of the devices to be compromised. Structure of PVK:TPA/PPV unbalances the injection of holes and electrons, but lowers the turn-on voltage.