Murlidhar. GOWIND. Takwale

Savitribai Phule Pune University | University of Poona · School of Energy Studies

This paper presents evaluation of a thermal performance of linear Fresnel Lens Solar Concentrator (FLSC) system for generation of low pressure steam for cooking and industrial process heat applications. Linear refracting type Fresnel lens was used to concentrate solar radiation on a receiver which is placed at the focal line. The Experimental inves...

The spray pyrolysis method is employed to deposit ZnO films at different precursor molarity (SC). The X-ray diffraction study reveals the polycrystalline film growth along [0 0 2], c-axis direction. The SC dependent variations of microstructural parameters are considered to propose the film's growth mechanism. The growth rate increases with SC due...

This communication presents the optical characterization of Co3O4 films electroplated on Cu and Ni coated Cu substrates. The Co3O4 films were successfully deposited by using the electrochemical deposition method with cobalt acetate tetrahydrate as a cobalt precursor followed by annealing at 350OC. As-prepared films were characterized using X-ray Di...

The Co3O4 films were successfully deposited by using electrochemical deposition method with cobalt acetate tetrahydrate as cobalt precursor followed by annealing at 350oC. As-prepared films were characterized using X-ray Diffraction, UV-visible spectroscopy, Fourier Transform Infra Red spectroscopy and Scanning Electron Microscopy. The characteriza...

Nanocrystalline ZnO thin films were deposited by intermittent spray pyrolysis using different alcoholic and aqua-alcoholic precursor solvents. The XRD analysis reveals the polycrystallinity of hexagonal wurtzite type ZnO films with preferred c-axis orientation along [002] direction. The polycrystallinity increased due to use of aqua-alcoholic precu...

Abstract : The demand for process heat particularly low pressure steam is increasing in recent past. Solar energy can be utilized for generating medium temperature (100°C -150°C) low pressure (T<200°C) steam. By using solar concentrators, low pressure steam can be generated by using low cost technology [1]. Fresnel lens solar concentrators are very...

Concentrating Solar Thermal (CST) is a unique renewable energy technology for medium/high temperature applications. CST systems have ability to provide electricity, refrigeration and water purification in one unit. This technology will be extremely helpful in improving the quality of life for many people around the world who lack the energy needed...

In this review, we present the state-of-the-art of the SiC based solar selective coatings used for solar thermal applications. The absorbers are coated with solar selective coatings with high absorptance and low thermal emittance. Spectrally selective coatings which are stable up to temperatures <300 degree C (in air and vacuum) have been developed...

Concentrating Solar Thermal (CST) is a unique renewable energy technology for medium/high temperature application. CST systems have the ability to provide electricity, refrigeration and water purification in one unit. This technology will be extremely helpful in improving the quality of life for many people around the world who lack the energy n...

Uniformly distributed jet of fine droplets was created with control of spray rate (Sf) to deposit nanocrystalline ZnO thin films by spray pyrolysis technique. X-ray diffraction analysis indicated the polycrystalline film growth with most preferred orientation along c-axis [0 0 2] direction for Sf ⩽ 4.5 ml/min, above which films favored [1 0 1] dire...

Nanocrystalline ZnO thin films were deposited at different temperatures (Ts = 325 °C–500 °C) by intermittent spray pyrolysis technique. The thickness (300 ± 10 nm) independent effect of Ts on physical properties was explored. X-Ray diffraction analysis revealed the growth of wurtzite type polycrystalline ZnO films with dominant c-axis orientation a...

The preparation of cobalt oxide (Co3O4) films containing 1-D interlinked nanowires by spray pyrolysis technique using cobaltous acetate (CH3COO)(2)Co center dot 4H(2)O solutions in 1:1 water-methanol mixture and study of their optical properties are reported in this paper. The films are characterized by using different physical techniques-X-ray dif...

The present communication reports the structural, optical and electrical properties of p-CdTe films deposited by using spray pyrolysis technique on thoroughly cleaned sodalime glass substrates at 350 °C in inert N2 atmosphere. The films were characterized by using XRD, Raman spectroscopy, XPS, thickness profiler, SEM, EDAX and UV–Visible spectrosco...

The preparation of Co3O4 films containing 1-D interlinked nanowires by electrochemical deposition technique using CH3COO)2Co.4H2O solutions in distilled water and study of their optical properties are reported in this paper. The films are characterized by using XRD, UV-visible & FTIR spectroscopies, XPS and SEM. The characterization studies showed...

In present paper, we report the preparation of CdTe films on thoroughly cleaned glass substrates by using the novel spray pyrolysis technique with CdCl2.H2O and TeO2 as precursor materials. The films were deposited on glass substrates by using the parameters: (a) spray nozzle - substrate distance = 30 cm, (b) sparing solution conc. = 0.02 M, (c) ca...

TiO2 thin films were deposited on glass substrates by sol-gel method. Nanocrystalline TiO2 thin films were prepared at ambient conditions and titanium tetraisopropoxide [C12H28O4Ti] was used as a Ti-precursor. The effect of annealing temperature on optical properties of nanocrystalline TiO2 thin films was studied. The as-deposited films were dried...

The Co3O4 films were prepared using two steps method. Initially, the films were deposited on thoroughly cleaned copper substrates by using pulsed DC electrochemical deposition method from a solution containing Co(NO3)2:6H2O and H3BO3. The films were deposited at different molar concentrations: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7 M of Co(NO3)2 in d...

The Co 3 O 4 films are prepared using two steps method. Initially, the films are electrochemically deposited on stainless steel and copper substrates from the solution containing CoSO 4 and H 3 BO 3 at various molar concentrations (0.05, 0.09, 0.13, 0.17, 0.21, 0.25 and 0.28 M) of CoCl 2 in deposition bath. These as-deposited films are transformed...

After-Fukushima incident, various concerns were raised by public and media about the safety of nuclear installations operating all around the world. All nuclear related eventualities of the past were meshed with the present, adding disproportionate factors, unrealistic conclusions were framed based mostly on notions. Fear of unknown radiation syndr...

Hydrogenated microcrystalline silicon with oxygen(mc-Si:O:H) is grown using radio frequency glow discharge method. Oxygen is introduced during growth by varying it's partial pressure in the growth chamber. The crystalline volume fraction ‘f’ and the crystallite size ‘δ’ are found to vary with the oxygen content. Results indicate that oxygen can etc...

Nanocrystalline undoped and Al doped ZnO thin films were synthesized by the chemical spray pyrolysis of Zinc acetate and Aluminium chloride solution. The optoelectronic properties of undoped and Al:ZnO films were investigated. The XRD patterns of films were preferably oriented along c-axis [0 0 2] plane with the hexagonal wurtzite structure. The Al...

Contact angle (CA) measurement is used as an empirical diagnostic method to pre-evaluate the performance of N3 related dye-sensitized solar cells. The method uses a 30 min sensitization of ZnO nanoplatelet-based electrodes, and the CA value of similar to 48 degrees is optimized for a maximum short-circuit current density of about 6.7 mA cm(-2). On...

Nanocrystalline ZnO films were synthesized by a chemical spray pyrolysis of zinc acetate solution. The deposition temperature (450degC) was kept constant by obstructing the spray after regular intervals. The XRD patterns of ZnO films were preferably oriented along c-axis (0 0 2) plane with the hexagonal wurtzite structure. The dependence of texture...

Silicon nitride films are deposited in presence of nitrogen gas plasma by ‘Activated Reactive Evaporation (ARE)’ process on silicon substrates maintained at room temperature. Silicon powder was evaporated by e-beam evaporation in the presence of nitrogen gas plasma excited by a radio frequency (RF) power source (13.56 MHz). Depositions were carried...

Highly transparent and conductive Boron doped zinc oxide (ZnO:B) thin films were deposited using chemical spray pyrolysis (CSP) technique on glass substrate. The effect of variation of boron doping concentration in reducing solution on film properties was investigated. Low angle X-ray analysis showed that the films were polycrystalline fitting well...

Hydrogenated amorphous silicon (a-Si:H) films were deposited using pure silane (SiH4) without hydrogen dilution by hot wire chemical vapor deposition (HW-CVD) technique. The electrical, optical, and structural properties of these films are systematically studied as a function of process pressure (Pr). The device quality a-Si:H films with a photosen...

Over the past few decades, Zinc Oxide (ZnO) has been emerged as transparent conducting oxide (TCO) materials for photovoltaic applications. The opto-electronic properties of ZnO can be improved by doping some suitable impurity ions their cations sites. We found that the aluminum (Al) is a suitable dopant in ZnO lattice to form ZnO:Al films. We repo...

Thin films of silicon oxynitride (SiOxNy) were deposited successfully on silicon wafer substrates using electron beam physical vapor deposition (EB-PVD) technique by varying the substrate temperature (T=100–450 °C) and deposition time (t=0.5–2.5 min). The films were characterized by UV–Visible and X-ray photoelectron spectroscopy (XPS), Tally step...

Hydrogenated amorphous silicon (a-Si:H) films were deposited using pure saline (SiH4) without hydrogen dilution by the hot wire chemical vapor deposition (HW-CVD) technique. The electrical, optical and structural properties of these films are systematically studied as a function of filament temperature (Tfil). The device quality a-Si:H films which...

Electron Beam Physical Vapor Deposited (EB-PVD) silicon oxynitride (SiOxNy) films of various compositions between SiO2 and Si3N4 were grown by changing the substrate temperature and deposition time The SiOxNy films were deposited at various temperatures ranging from 100°C to 400°C on single crystal wafer ( single side polish)and soda lime glass sub...

Hydrogenated amorphous silicon germanium (a-SiGe:H) films were deposited using SiH4 and GeH4 mixture without H dilution by hot wire chemical vapor deposition (HW-CVD) technique. The electrical, optical and structural of these films are systematically studied as a function of substrate temperature (Tsub). The FTIR spectroscopic studies showed that a...

Multilayer structures of the type a-Si:H/μc-Si:H were fabricated for the first time by hot wire chemical vapor deposition (HW-CVD) technique. These multilayers were studied for their opto-electronic and photovoltaic properties as a function of a-Si:H sublayer thickness. The microcrystalline phase of a-Si (μc-Si:H) of thickness 250 Å have been used...

In this letter, we report narrow band gap (1.39–1.53 eV) a-SiGe:H films with high photosensitivity (∼104–105) are grown successfully by HW-CVD using a mixture of (GeH4+SiH4) at low flow rates and without hydrogen dilution with higher deposition rates (>10 Å/s). These films are characterized by Raman spectroscopy, FTIR spectroscopy and UV–Visible sp...

The electrical, structural and optical properties of hydrogenated amorphous silicon (a-Si:H) films deposited from pure silane (SiH4) using hot wire chemical vapor deposition (HW-CVD) technique are systematically studied as a function of silane flow rate FSiH4 between 5 and 30sccm. We found that the properties are greatly affected by the silane flow...

The electrical, structural and optical properties of undoped and phosphorus doped μc-Si:H films prepared by a HW-CVD technique have been studied. The hydrogen (H2) dilution of silane has been varied carefully to produce undoped μc-Si:H films. The amorphous-to-microcrystalline transition was observed for a hydrogen dilution ratio >0.75. The phosphor...

Obtaining thickness uniformity over a large substrate area seems to be a bottleneck as far as the industrial applications of the hot-wire CVD (Cat-CVD) process is concerned. In order to address the different issues in this respect, we have simulated the hot-wire CVD growth process and proposed a proper filament geometry for maximum thickness unifor...

Transparent conducting oxide (TCO) films are useful as transparent electrodes in various electro-optical devices, solar cells, window coating, etc. Properties of TCO differ from one technique to another because of various process parameters involved during the deposition or post-deposition treatment of these films. But for all, the aim is to achiev...

CW CO2 laser annealing of boron-doped polycrystalline silicon at various substrate temperature, from room temperature to 600 degrees C, is reported. The overall improvement in charge carrier conduction of polycrystalline silicon is shown to occur at a substrate temperature of 200 degrees C, where the maximum improvement is observed in the charge ca...

Boron-doped hydrogenated microcrystalline silicon (μc-Si:H) films were prepared using hot-wire chemical vapor deposition (HWCVD) technique. Structural, electrical and optical properties of these thin films were systematically studied as a function of B2H6 gas (diborane) phase ratio (Variation in B2H6 gas phase ratio, dopant gas being diluted in hyd...

Undoped a-SiGe : H films were deposited by the RF plasma chemical vapor deposition method. Films deposited at different substrate temperatures ranging between 100°C and 300°C were studied for their optoelectronic and structural properties. Structural defects like vacancies and microvoids were studied by positron lifetime spectroscopy (PLTS) at room...

The properties of a-SiGe:H films prepared by the glow discharge plasma CVD method at various interelectrode separation were studied systematically. This study was done at two different rf power densities. It has been found that interelectrode separation plays an important role in determining film properties. It shows a more marked effect on photose...

Boron doped p-type hydrogenated microcrystalline silicon (μc-Si:H) films have been prepared by radio-frequency glow discharge method. Highly conductive p-type μc-Si:H films can be obtained even with lower concentration of hydrogen in the rf glow discharge plasma if chamber pressure is low. Effects of increase in hydrogen (H2) flow rate and chamber...

A large scale forced convection solar drying system has been designed and fabricated, comprising an array of forty solar collectors and three drying cabinets with a blower. Such a system yields 300 kg of dry product of custard powder in a normal sunshine day. It is shown that such a system is feasible and has an ability to save large amounts of fue...

Fluorine-doped indium oxide films were prepared by the spray pyrolysis technique. The physical properties of these films were investigated with respect to various process parameters, namely variation of dopant concentration (in the solution), deposition temperature (T s), carrier gas (air) flow rate and the thickness of the film. The best films had...

In this paper, we analyse the performance of a suspended plate solar air heater working at low and moderate temperatures with a fluid flow on both sides of the absorber plate. A theoretical model for the system and subsequent numerical analysis of the system is presented in steady state. Some experimental measurements of the fabricated collector un...

Field electron emission from a hydrogenated amorphous silicon deposited tungsten tip has been studied. The effect of prolonged (hourly) exposure to light on the field electron emission current has been investigated. The current‐voltage characteristics of the as‐deposited, light exposed, and annealed states of the emitter showed semiconducting behav...

Waste disposal in a developing country such as India is a menace, due to the large quantity of waste generated and the poor suitability of methods available. The anaerobic method of digestion is one of the more viable modes of waste handling, although the efficiency is much lower than that achieved in the aerobic mode, in terms of suitability for d...

Transparent conducting films of In2O3 have been prepared by the electron beam evaporation technique (EBET) at a substrate temperature of -25 °C. As-deposited films are dark in colour. Subsequent heat treatment of these films in air resulted in crystallization of all films. In order to obtain more insight into the annealing phenomenon, three series...

Black cobalt deposits were formed on glass substrates for use in all glass evacuated collectors. Glass was made conducting by depositing fluorine doped tin oxide films using spray pyrolysis. The reflectivity of this glass was further improved by electroplating a thin nickel layer (0.35 μm) on it. Cobalt oxide thin films were deposited on these nick...

Antimony‐doped tin oxide films were deposited by spray pyrolysis technique. The effect of antimony doping on structural and electrical properties was investigated in detail using the x‐ray diffraction technique and room‐temperature Hall measurements. Antimony doping did not affect the preferred growth along [200] to a considerable extent. These res...

Antimony-doped tin oxide films were deposited by spray pyrolysis on Corning 7059 substrates. The structural and electrical properties of the films deposited with different doping levels were studied. Relative variations in the structural properties were explained on the basis of structure factor calculations. The results show that the incorporation...

Indium-doped zinc oxide (IZO) films were prepared by the spray pyrolysis technique. The effect of gradual incorporation of indium cations on the structural, electrical, and compositional properties of IZO films was studied in detail. It was observed that even a small addition of indium modifies the preferred growth of IZO film from the [002] direct...

Indium oxide films were deposited by an electron beam evaporation technique on Corning® glass substrates at various substrate temperatures ranging from 25 to 300 °C. As-deposited films appeared to be dark or semitransparent; whether they were amorphous or polycrystalline depended on the substrate temperature. In order to obtain good opto-electronic...

Using the spray pyrolysis technique thin films of indium oxide were prepared on Corning glass (7059) at a substrate temperature of 425 °C at different flow rates. The electrical and structural properties of these films were studied. The Hall measurements at room temperature showed that the films prepared in an air flow rate of 7 litre min−1 have th...

As-deposited thin films of SnO 2 with substrate temperatures of 50, 200 and 350°C revealed that the films required an additional step of annealing to change the SnO 2 phase to SnO 2 with acceptable optical and electrical properties. Films deposited at 350°C and annealed at 650°C for 2h met the desired requirements

Indium-doped zinc oxide (IZO) films were deposited on Corning 7059 substrates by the spray pyrolysis technique. To achieve higher electrical conductivity both the zinc acetate concentration and indium concentration in the solution were varied. The films were characterized for their structural and electrical properties. Film stability in H2 plasma w...

For highly conducting transparent films, thickness is an important parameter. This investigation optimizes the film thickness to obtain high electrical conductivity without appreciably affecting the transparency. Undoped Indium oxide films having different thickness have been deposited on Corning glass (7059) by using the spray pyrolysis technique....

Hydrogenated and oxygenated microcrystalline silicon (mc‐Si:O:H) is prepared by rf glow discharge method with a mixture of silane, hydrogen, and oxygen. It is observed that the Hall mobility for the films can be ∼35 cm² V^-1 s^-1 under optimal oxygen contents. When used as i layer in a p‐i‐n solar cell configuration,...

Thin films of undoped In2O3 have been deposited at different substrate temperatures using the spray pyrolysis technique. These films show a preferred orientation which depends upon the deposition temperature of the substrate. The number of charge carriers and their mobility for the films have been measured and attempts have been made to explain the...

Aluminum---doped zinc oxide films were prepared on Corning 7059 by an inexpensive spray pyrolysis technique. Variation in structural, electrical and optical properties with doping concentration is investigated in detail. The films were highly transparent to the visible radiation and electrically conductive. X-ray diffraction results show that all f...

In order to probe into the growth mechanism of sprayed SnO 2 films, the films were deposited with different Sn concentrations in the precursor solution. The orientational properties were determined using grazing incidence x‐ray diffraction. The preferred growth changed from [110] to [200] direction as the Sn incorporation was increased. Such a chan...

Transparent conducting tin oxide films were prepared by an electron beam evaporation technique. As-deposited films were amorphous or polycrystalline depending on the substrate temperature and the time of deposition. In order to get transparent and conducting thin films of SnO2, as-deposited films were subjected to further heat-treatment in air at 6...

Tin oxide thin films were deposited by the spray pyrolysis technique on Corning 7059. The X-ray diffraction results indicated that all deposited films were polycrystalline with a tetragonal (rutile) structure. The films showed preferred [200] orientation irrespective of the deposition conditions for a fixed solution composition. Hence, attempts wer...

In order to probe into the growth mechanism of sprayed SnOâ films, the films were deposited with different Sn concentrations in the precursor solution. The orientational properties were determined using grazing incidence x-ray diffraction. The preferred growth changed from (110) to (200) direction as the Sn incorporation was increased. Such a chang...

Hydrogen passivation of grain boundaries in polycrystalline silicon is shown to improve the efficiencies of devices fabricated from these materials. We have carried out hydrogen plasma passivation of polycrystalline silicon in RF discharge and have studied the variation in room temperature resistivity of the polysilicon wafer after H plasma treatme...

Hydrogen passivation of polycrystalline silicon wafer is carried out in order to reduce the deleterious effects of grain boundaries. A systematic variation is made in the process parameters implemented during hydrogen passivation and the results of room temperature resistivity measurements are reported. As an efficient tool to study the structure c...

Transparent and conducting thin films of tin oxide have been deposited by spray pyrolysis on Corning 7059 substrates. The films were investigated by X-ray diffraction and Seebeck measurements to study the structural and electrical transport properties. The films were polycrystalline and the oxide phase observed was SnO2 in cassiterite structure. Th...

Thin films of SnO2 and SnO2: F were deposited by a spray pyrolysis technique. The effect of substrate temperature on the structural and electrical transport properties of these films was investigated.The standard deviation of these films from ASTM data explains the growth mechanism with other process parameters at optimum values.

We report detailed studies of hydrogen passivation of polycrystalline silicon wafers by RF plasma and the effect of various process parameters on the extent of passivation as seen through electrical measurements. Similar studies made on polysilicon solar cells are also reported. The need for such studies is emphasized via some interesting results w...

Transparent and conducting thin films of SnO2 and SnO2: F were deposited on alkali-free Corning 7059 substrates by spray pyrolysis. The effect of various process parameters such as doping level of fluorine (in solution), substrate temperature during deposition, thickness of the film and carrier gas (air) flow rate, on the film properties was invest...

A study of a series of chemiplated CuxS films deposited on varying CdS film structures and under different deposition parameters by electro-chemical analysis was carried out. A morphological model was developed. This study provided a complementary method for distinguishing grain surface and grain boundary growth. Values of grain surface and grain b...

This report deals with electrical and structural properties of sprayed CdS films produced under varying process parameters such as pyrolysis temperature, solution concentration and film thickness. The number of traps appears to depend on the structural quality factor of the CdS films. However, electrical properties are dependent on the presence of...

Excess of cadmium was incorporated in sprayed CdS films by appropriately varying the solution composition. Its effect on the electrical and structural properties of the films has been studied. It appears that excess cadmium segregates at the grain boundaries, thereby changing the electrical properties. Similarly, introduction of oxygen, which is an...

The spectral selectivity and optical properties of a structured (multilayer) coating comprising an anodized porous Al2O3 film sequentially impregnated with zinc and nickel on an aluminium substrate were theoretically investigated employing the effective media concept and using the Maxwell Garnett and Bruggeman approaches to determine the dielectric...

Nickel-impregnated anodized Al2O3 films on aluminium substrates were investigated as possible selective coatings for the photothermal conversion of solar energy. A purely chemical dip process for producing these spectrally selective coatings was developed as an alternative to the electrochemical process reported earlier. The process parameters were...

Vacuum-evaporated bismuth films were bombarded with (non-penetrating) N+2 ions and the oxidation behaviour of these films during a subsequent thermal treatment was studied. The incorporation of oxygen in the films at a fixed temperature was indirectly monitored by measuring the variation in the electrical resistance with the oxidation time. The oxy...