Sunit Rane

Firing and processing effects on microstructure of fritted silver thick film electrode materials for solar cells

Thick film materials (viz. conductor, resistor, dielectric and solder pastes) have been proved to possesses economical processing and functional advantages over other technologies in high volume and quick turn-around production of hybrid microelectronic circuits. Silver thick films are widely used for the front electrode metallization of silicon solar cells. This paper reports the microstructural, physico-chemical and electrical properties of the fritted silver thick film electrode materials (for silicon solar cells) formulated using different processing conditions, which also included treatment with surfactants.

A study on sintering and microstructure development of fritless silver thick film conductors

Thick film materials have proved to possess economic processing and functional advantages over other technologies in high-volume production of miniaturized circuits. The development of a low-cost fritless silver paste with different binder composition is described in the present work. The effect of composition and firing temperature (700–900 °C) on the microstructure is also reported. The sheet resistivity and surface morphology of all the indigenously formulated Ag thick film pastes are compared with the imported (ESL) paste. The results suggest that the thick films can be fired at 700 °C instead of the conventional 900 °C firing temperature.

Thick film NTC thermistor for wide range of temperature sensing

Purpose – Aims to focus on temperature sensors.Design/methodology/approach – Negative temperature co‐efficient thermistor powders of ternary Mn, Co, Ni oxide along with RuO2 synthesized at relatively moderates temperature (1,000°C). Thick film thermistor paste compositions were formulated by mixing the semiconducting oxide powder, glass frit and organic vehicle. The physico‐chemical analysis, viz. X‐ray diffraction, scanning electron microscopy and thermogravimetry and IR spectroscopy were carried out for the synthesized powder and the resultant thick films. The X‐ray analysis of the powders showed the cubic spinel structure. The electrical properties like thermistor constant, sensitivity index and activation energy of the thick film NTC thermistor were determined.Findings – The room temperature resistance is observed to range from 490 KΩ to 4.13 MΩ with thermistor constant ranging from 3,275 to 3,980 K, in the temperature range of 25‐300°C.Originality/value – Describes research work on temperature sensor...

One dimensional CdS/ZnO nanocomposites: an efficient photocatalyst for hydrogen generation

One-dimensional ZnO nanostructures were synthesized using solvothermal reaction method, and in situ CdS nanoparticles were grown on 1D ZnO having different CdS compositions such as 0.1, 0.5, 1 and 5 mol% using microwave reaction system. The prepared CdS/ZnO coupled semiconductor catalysts were characterized using various spectroscopic techniques. XRD analysis indicated the presence of a wurtzite structure for all the prepared CdS/ZnO compositions. DRS spectrum showed red shift in the absorbance edge of CdS/ZnO nanocomposites with increasing CdS mol% and absorbance increases in 400 to 500 nm range. Photoluminescence spectra illustrated two emission peaks, with the first one at 390 nm due to the band edge emission of ZnO and the second broad peak centered around 480 nm possibly due to CdS band edge emission or oxygen vacancies in ZnO. FESEM image showed the formation of pencil shaped one-dimensional ZnO nanorods containing spherical CdS nanoparticles on the surface of ZnO. TEM analysis confirms the rod-like morphology of ZnO and the presence of CdS nanoparticles. The activity of the prepared CdS/ZnO catalysts was evaluated by measuring the amount of H2 generated during photocatalytic H2 evolution from water. The photocatalytic activity of prepared coupled CdS/ZnO shows an increase in hydrogen generation compared to that of individual ones. CdS loading enhances the rate of H2 generation and is the highest for 5 mol% CdS/ZnO composition.

Thin film, thick film microstrip band pass filter: a comparison and effect of bulk overlay

Abstract This paper reports the comparison of two fabrication techniques (viz. thin and thick film) for microstrip broadband filter in the X-band. The effect of bulk Al2O3 overlay (in pellet form and at different positions) on the characteristics of the broadband filter is also reported in this paper. The characteristics vary with the overlay position and thin film circuits seem to be more affected than thick film circuits.

Thick film microstrip rejection filter with improved Q using overlay

In this paper studies on the lab formulated fritless silver thick film paste with two different binder compositions that have been used to fabricate λ/2 microstrip rejection filter in the X and Ku band are reported. These have been compared with ESL (USA) paste and copper thin film metallization for the same circuit. The thick film circuits were overlayed with TiO2 thick film of different thickness and changes in the characteristics studied. In the X band, the Q of the filter improves with overlay and is also dependent on the Ag paste formulation, whereas in the Ku band there are no thick film paste dependent properties observed due to overlay. Thickness of overlay and metallization paste formulation dependent factors should be taken into consideration during fabrication of high density and multi‐layer microwave integrated circuits.

Solar light driven dye degradation using novel organo–inorganic (6,13-pentacenequinone/TiO2) nanocomposite

The coupled semiconductor photocatalysts of 6,13-pentacenequinone/TiO2 (PQ/Ti) with different weight ratios were prepared. The PQ/TiO2 nanocomposite was prepared by a simple wet impregnation method. The prepared catalyst was characterized with various spectroscopic methods. XRD confirms the monoclinic and anatase phase of PQ and TiO2, respectively. FE-SEM showed the sheet like morphology of PQ, whereas the coupled catalyst depicts the formation of a homogeneous layer of TiO2 on the PQ surface in all three compositions. Optical studies by diffuse reflectance UV-Visible absorbance spectroscopy (DRS) indicate the band gap of PQ and TiO2 around 2.8 and 3.2 eV respectively. The absorbance in the range of 450 nm was also observed in the case of the prepared coupled catalyst confirming the loading of PQ on TiO2. The photocatalytic activity of the coupled catalyst was studied by observing the degradation of methylene blue (MB) dye under visible light irradiation. As compare to the individual components, the coupled organo–inorganic catalyst showed higher photocatalytic activity towards MB degradation. The PQ/TiO2 nanocomposite having 0.2 wt% PQ showed the highest rate of MB degradation i.e. Kapp = 5.2 × 10−2 min−1.

Moisture ambient effects on an Al2O3 thin-thick film overlaid parallel coupled broad-band microstrip filter

This paper reports the behaviour of a parallel coupled band pass microstrip filter due to an Al2O3 thin film‐thick film overlay and the effect of the moisture ambient on the properties of the overlaid microstrip filter. The thickness of the initial thin‐film overlay affects the behaviour of the filter after thick‐film overlay. Moisture has the effect of lowering the transmittance drastically and shifting the pass band to the lower frequency end. The filter loses its band pass characteristics after a few moisture‐heat cycles, indicating irreversible change taking place in the overlay material. It is felt that the ageing aspects of the overlay material should be taken into account when using dielectric overlays for circuit protection and cross‐over insulation purposes.

Hydrogen, ethanol and ammonia gas sensing properties of nano-structured titanium dioxide thick films

Pure nanocrystalline TiO2 thick films have been prepared by doctor blade technique on glass substrate. The nanostructural properties of the powder as well as thick films and gas sensing performance of the TiO2 thick films towards hydrogen, ethanol and ammonia gases have been studied and presented here. The experimental results revealed that these nanostructured TiO2 films are sensitive to different gases such as hydrogen, ammonia and ethanol at low operating temperature close to 55–65 °C. The TiO2 film shows highest sensitivity towards ammonia gas as compared to hydrogen and ethanol.

Study of Ku-band Properties of AL2O3 and Nb2O5 Pellet Overlayed Microstriplines of Different Widths

The Ku-band behaviour of microstriplines of widths 16 mil, 18 mil, 20 mil due to pellet overlay of Al2O3 and Nb2O5 are reported in this paper. Above 16.5 GHz the lines are highly dispersive. The effect of overlay is to give frequency dependent changes in transmittance. The losses are dependent on microstripline width and also thickness of overlay. The dielectric constant of the overlay material does not seem to affect the properties of the microstripline. It is felt that at higher frequencies consideration has to be given to the width of microstripline and also on the material used as overlay to get improved properties of the circuit.