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The article titled "Retraction Note: An adaptive neuro-fuzzy logic based jamming detection system in WSN" has been retracted by the publisher due to concerns about compromised editorial handling and peer review processes. The authors, K. P. Vijayakumar, P. Ganeskumar, P. Vijayakumar, and T. Karthick, have not responded to correspondence regarding the retraction. The retraction note highlights issues with inappropriate references and being out of scope for the journal or guest-edited issue. [Extracted from the article]

Information and Communication Technology (ICT) can be used as a potential tool to develop rural India, but the awareness and positive attitude towards the facilities offered by it is a necessity to use it to the full potential. The study tries to analyze the awareness of farmers about the various ICT tools in agriculture. Survey using questionnaire was resorted to collect data from user group. The user group under consideration consists of farmers registered to four KrishiBhavans in Nedumangad block, Thiruvananthapuram District of Kerala. Farmers with more than 1 acre of land registered in KrishiBhavans in the four selected blocks were 1040. From them, a sample size of fifteen percentages (156) of farmers is selected. Data obtained through questionnaire was tabulated, analyzed and interpreted using Microsoft Office Excel 2010 and SPSS 20. Chi-square test was applied for finding significant association between the categorical variables. [ABSTRACT FROM AUTHOR]

Wireless sensor network (WSN) is employed in variety of applications ranging from agriculture to military. WSN is vulnerable to various security attacks, in which jamming attacks obstruct and disturb the exchange of information between sensor nodes in WSN by transmitting signals to jam legitimate transmission to cause a denial of service. Hence, it is essential to secure the sensor networks from jamming attacks. In this paper, two approaches: fuzzy inference system (FIS) and adaptive neuro-fuzzy inference system (ANFIS)-based jamming detection system are proposed for detecting the presence of jamming by computing two jamming detection metrics, namely, packet delivery ratio and received signal strength indicator. FIS approach is based on Takagi–Sugeno fuzzy logic which optimizes the jamming detection metrics. ANFIS approach combines fuzzy logic and learning ability of the neural network to optimize the metrics for detecting various types of jamming. The proposed approaches are compared with existing system and themselves. The simulation result shows that the proposed ANFIS approach detects the jamming attacks as high as true detection ratio. [ABSTRACT FROM AUTHOR]

Presents information on a study which used ellipsometry to study the variation in the irregularities at the interface of copper sulfphide/cadmium sulphide thin films. Methodology of the study; Results and discussion; Conclusion.

In this paper, a fuzzy logic--based jamming detection algorithm (FLJDA) is proposed to detect the presence of jamming in downstream data communication for cluster-based wireless sensor networks. The proposed FLJDA keeps an eye on the existing nodes and new node to determine their behavior by applying fuzzy logic on measured jamming detection metrics. To monitor the behavior of the nodes, the FLJDA computes the jamming detection metrics, namely, packet delivery ratio and received signal strength indicator. The major features of this paper are the following: (1) The jamming detection algorithm is specifically implemented for downstream data communication, (2) cluster head estimates jamming detection metrics for detecting the jamming unlike the existing algorithms where individual nodes explicitly collect the jamming detection metrics, and (3) the proposed algorithm optimizes the jamming detection metrics on the basis of fuzzy logic unlike the existing approaches, which uses merely jamming detection threshold alone for jamming detection. The simulation results of the proposed system provide the true detection ratio as high as 99.89%. [ABSTRACT FROM AUTHOR]

Presents a study which proposed an optical method involving ellipsometry to measure stress in silver films of different thickness. Experiment; Results and discussion; Conclusion.

Origin of the well-known blue-green emission of spray pyrolysed ZnO thin films has been discussed on the basis of variation of the properties due to different treatment of the samples such as ion beam irradiation and doping. 120 MeV Au ions and 80 MeV Ni ions were used for ion beam irradiation while indium was used for doping studies. It was assumed that, Au ions might have produced huge amount of defects while the defects might be less in Ni irradiated films due to the difference in energy and mass number. Photoluminescence studies of pristine sample showed only one emission at 517 nm at room temperature while the irradiated films showed a decrease in intensity of this emission. Indium doping also reduced the intensity of this emission. But additional emissions were also observed in these films. Based on the observations, we proposed that the blue-green emission was due to the transition from conduction band to the level due to oxygen antisite (OZn). [ABSTRACT FROM AUTHOR]

Effect of thermal diffusion of indium in ZnO thin films, prepared using spray pyrolysis technique, is discussed. ZnO:In films were characterized using different techniques such as x-ray diffraction (XRD), photoluminescence, electrical resistivity measurements, and optical absorption and transmission. The XRD analysis showed that all the films had a preferred (002) orientation. There was no considerable change in peak height or full width at half maximum, due to the variation in doping percentage. Peak positions corresponding to (002) and (101) planes were slightly shifted to lower 2θ values. Optical band gap also decreased slightly with indium concentration, and for higher indium concentration percentage of transmission reduced very much. Drastic decrease in resistivity was observed and two activation energies (30 and 15 meV) were obtained for the doped samples. These levels were identified as due to zinc interstitials and/or due to indium at zinc lattice and impurity related defect levels. Photoluminescence measurements gave two emissions. In this, one was the near band-edge (NBE) emission and the other was the blue-green emission. As doping concentration increased, the NBE emission shifted to higher wavelength while the blue-green emission was shifted to lower wavelength (blueshift). [ABSTRACT FROM AUTHOR]

Spray pyrolyzed ZnO films prepared using solution containing ethanol and water (volume ratio 1:1), exhibited optical transmission of 85% in the visible range and electrical resistivity of 78 Ω cm. These samples were irradiated using 120 MeV Au ion beam and then characterized using optical absorption and transmission, x-ray diffraction (XRD), electrical resistivity measurements, x-ray photoelectron spectroscopy (XPS), and photoluminescence studies. It appears that irradiation does not affect absorption edge while optical transmittance was slightly reduced. But intensities of peaks of XRD and photoluminescence were found to decrease continuously with increasing ion fluence. Electrical resistivity of the films decreased considerably (from 78 to 0.71 Ω cm) with increase in ion fluence. Atomic concentration from XPS analysis showed that Zn/O ratio is getting increased due to ion beam irradiation. Variations in carrier concentration were also measured using Hall measurements. [ABSTRACT FROM AUTHOR]

Analyses the size and structure of the professional and non-professional manpower in the five university libraries of Kerala. It examines the staff pattern, categorisation of manpower and their salary scales, qualifications prescribed for each category, general and professional qualifications possessed by them and present strength of professional and non-professional manpower. It also suggests urgent measures to be taken to rectify the anomalies in the present situation. [ABSTRACT FROM AUTHOR]

ZnO thin films, irradiated by 80 MeV Ni+ ions, were analysed with the help of different characterization techniques like X-ray diffraction, optical absorption, transmission, photoluminescence (PL), electrical resistivity, photosensitivity (PS) and thermally stimulated current (TSC) measurements. Crystallinity and absorption edge were hardly affected by irradiation. PL spectrum of pristine sample showed a broad peak at 517 nm, whereas irradiated film had two emissions at 517 and 590 nm. Intensity ratio between these two emissions (I517/I590) decreased with the fluence, and finally at a fluence of 3×1013 ions/cm2, the emission at 517 nm completely disappeared. Electrical resistivity of the sample irradiated with a fluence of 1×1013 ions/cm2 drastically increased. However, on increasing the fluence to 3×1013 ions/cm2, resistivity decreased, probably due the onset of hopping conduction through defects. PS also decreased due to irradiation. TSC measurements on pristine sample could reveal only one defect level at 0.6 eV, due to interstitia1 zinc (ZnI). But, irradiation at a fluence of 1×1012 ions/cm2, resulted in three different defect levels as per TSC studies. Interestingly, the sample irradiated at a fluence of 3×1013 ions/cm2 had only one defect level corresponding to a deep donor. The possible origin of these defect levels is also discussed in the paper. [ABSTRACT FROM AUTHOR]

We report a new structure for CuInS2/In2S3 solar cell, in which both absorber and buffer layers were deposited using chemical spray pyrolysis (CSP) technique. The usual superstrate structure, having buffer layer just above ITO, was not functioning mainly due to diffusion of Cu into In2S3 layer as seen from X-ray photoelectron spectroscopy (XPS) results. However, when the configuration of the cell was ITO/CuInS2/In2S3/Ag, cell parameters obtained were Voc=0.45 V, Jsc=44.03 mA/cm2, fill factor (FF) = 29.5% and η=5.87%. Good results could be obtained by using indium sulfide thin films having maximum photosensitivity. The cell was characterized using X-ray diffraction, optical absorption, current–voltage and spectral response measurements. [ABSTRACT FROM AUTHOR]

Most of the existing peer-to-peer (P2P) content distribution schemes carry out a random or rarest piece first content dissemination procedure to avoid duplicate transmission of the same pieces of data and rare pieces of data occurring in the network. This problem is solved using P2P content distribution based on network coding scheme. Network coding scheme uses random linear combination of coded pieces. Hence, the above-stated problem is solved easily and simply. Our proposed mechanism uses network coding mechanism in which several contents having the same message are grouped into different groups and coding operation is performed only within the same group. The interested peers are also divided into several groups with each group having the responsibility to spread one set of contents of messages. The coding system is designed to assure the property that any subset of the messages can be utilized to decode the original content as long as the size of the subset is suitably large. To meet this condition, dynamic smart network coding (DSNC) scheme is defined which assures the preferred property, then peers are connected in the same group to send the corresponding message, and connect peers in different groups to disseminate messages for carrying out decoding operation. Moreover, the proposed system is readily expanded to support topology change to get better system performance further in terms of reliability, link stress and throughput. The simulation results prove that the proposed system can attain 20–25% higher throughput than existing systems, good reliability, link failure and robustness to peer churn. [ABSTRACT FROM AUTHOR]

Nonradiative transitions occurring in semiconductors result in thermal emissions carrying information on the material’s thermal and electronic properties. A simple one-dimensional theoretical model is devised which accounts for the photothermal signal variations due to nonradiative transitions occurring in semiconductor thinfilms. The theory was verified by determining the transport properties of p-type silicon wafer. We could get the thermal diffusivity, minority carrier lifetime, surface recombination velocity, and minority carrier mobility of CuInS2 thin films, thereby proving the efficiency and simplicity of photothermal beam deflection technique for real time characterization of semiconductor thin films. The film fabrication history, composition, and post deposition treatments play crucial role in determining the transport properties and the effect of these conditions on transport properties of the film as well as on the solar cell parameters is discussed. [ABSTRACT FROM AUTHOR]

Highly photoconducting β-In2S3 thin films with conducting grain boundaries were obtained, using “chemical spray pyrolysis” technique. By varying the atomic ratio of the precursor solution used for spray pyrolysis, the photoconductivity of these films could be tailored. Conducting grain boundaries were found only for samples with a specific stoichiometry and these films exhibited photoresponse to intrinsic and extrinsic excitation wavelengths in the range of 325–532 nm. Postdeposition vacuum annealing of these films enhanced the grain boundary conductivity, caused the films to exhibit persistent photoconductivity for both intrinsic and extrinsic excitations and extended the extrinsic photoresponse to wavelengths beyond 632.8 nm. Photoresponse to excitation wavelength of 632.8 nm was observed in films with and without conducting grain boundaries which proved that the extrinsic photoresponse to this wavelength was an effect associated with the defect chemistry of the β-In2S3. [ABSTRACT FROM AUTHOR]

γ-In2Se3 thin films prepared at different annealing temperatures ranging from 100 to 400 °C were irradiated using 90 MeV Si ions with a fluence of 2×1013 ions/cm2. X-ray diffraction analysis proved that there is no considerable variation in structural properties of the films due to the swift heavy ion irradiation. However, photosensitivity and sheet resistance of the samples increased due to irradiation. It was observed that the sample, which had negative photoconductivity, exhibited positive photoconductivity, after irradiation. The negative photoconductivity was due to the combined effect of trapping of photoexcited electrons, at traps 1.42 and 1.26 eV, above the valence band along with destruction of the minority carriers, created during illumination, through recombination. Photoluminescence study revealed that the emission was due to the transition to a recombination center, which was 180 meV above the valence band. Optical absorption study proved that the defects present at 1.42 and 1.26 eV were annealed out by the ion beam irradiation. This allowed photoexcited carriers to reach conduction band, which resulted in positive photoconductivity. Optical absorption study also revealed that the band gap of the material could be increased by ion beam irradiation. The sample prepared at 400 °C had a band gap of 2 eV and this increased to 2.8 eV, after irradiation. The increase in optical band gap was attributed to the annihilation of localized defect bands, near the conduction and valence band edges, on irradiation. Thus, by ion beam irradiation, one could enhance photosensitivity as well as the optical band gap of γ-In2Se3, making the material suitable for applications such as window layer in solar cells. [ABSTRACT FROM AUTHOR]

β-In2S3 thin films with a band gap of ∼2.67 eV exhibited persistent photoconductivity when excited using photons with energy of 1.96 eV. The photoconductive response to extrinsic photoexcitation could be removed when the film stoichiometry was changed. Photoluminescence studies in the films revealed an emission of 1.826 eV, due to donor–acceptor pair (DAP) recombination, which was absent in the film not responding to extrinsic excitation. Hence, it was concluded that presence of the DAP was responsible for the extrinsic photoconductivity under the 1.96 eV excitation. This study can initiate further a methodology for tailoring the photoresponse of this semiconducting thin film by spatially controlling the film stoichiometry. [ABSTRACT FROM AUTHOR]

The effect of doping spray pyrolyzed thin films of In2S3 with silver is discussed. It was observed that silver diffused into In2S3 films in as deposited condition itself. Depth profile using x-ray photoelectron spectroscopy clearly showed diffusion of silver into In2S3 layer without any annealing. X-ray analysis revealed significant enhancement in crystallinity and grain size up to an optimum percentage of doping concentration. This optimum value showed dependence on thickness and atomic ratio of indium and sulfur in the film. Band gap decreased up to the optimum value of doping and thereafter it increased. Electrical studies showed a drastic decrease in resistivity from 1.2×103 to 0.06 Ω cm due to doping. A sample having optimum doping was found to be more photosensitive and low resistive when compared with a pristine sample. Improvement in crystallinity, conductivity, and photosensitivity due to doping of spray pyrolyzed In2S3 films with Ag helped to attain efficiency of 9.5% for Ag/In2S3/CuInS2/ITO (indium tin oxide) solar cell. [ABSTRACT FROM AUTHOR]

Negative photoconductivity in indium selenide (γ-In2Se3) thin films was observed at room temperature and was attributed to trapping of electrons and destruction of minority carriers during illumination through recombination. Photoconductivity of the films exhibited a strong dependence on the concentration of indium in the films. Photoconductivity decreased gradually and became negative as indium concentration increased. But there was no considerable variation in the optical band gap (1.84 eV) of the films, on varying indium concentration. Increase of indium concentration introduced defect levels at 1.46 and 1.32 eV above the valance band. Photoluminescence study revealed the emission to a recombination center, which is situated at 290 meV above valance band for all the samples. Levels at 1.46 and 1.32 eV prevented photogenerated carriers from reaching conduction band, during illumination. Thus the capture of conduction band electrons and destruction of minority carries via recombination, resulted in negative photoconductivity. [ABSTRACT FROM AUTHOR]

Infrared photoluminescence (PL) emissions centered at 1550 and 1564 nm were obtained at 15 K from CuInSe2/indium tin oxide heterostructure. PL studies revealed transitions between donor-acceptor pairs and band to acceptor to be the origin of the 1550 and 1564 nm emissions, respectively. At low temperatures (15–60 K) the 1550 nm emission was prominent. Upon increasing the excitation intensity at low temperature the 1564 nm emission gained prominence. Increase in temperature also caused the 1564 nm emission to gain significance. The possibility of selecting one of the two emissions by adjusting temperature or excitation intensity is discussed. [ABSTRACT FROM AUTHOR]

Single-carrier frequency division multiple access (SC-FDMA) systems with space frequency block coding (SFBC) transmissions achieve both spatial and frequency diversity gains in wireless communications. However, SFBC SC-FDMA schemes using linear detectors suffer from severe performance deterioration because of noise enhancement propagation and additive noise presence in the detected output. Both issues are similar to inter-symbol-interference (ISI). Traditionally, SC-FDMA system decision feedback equalizer (DFE) is often used to eliminate ISI caused by multipath propagation. This article proposes frequency domain turbo equalization based on nonlinear multiuser detection for uplink SFBC SC-FDMA transmission systems. The presented iterative receiver performs equalization with soft decisions feedback for ISI mitigation. Its coefficients are derived using minimum mean squared error criteria. The receiver configuration study is Alamouti's SFBC with two transmit and two receive antennas. New receiver approach is compared with the recently proposed suboptimal linear detector for SFBC SC-FDMA systems. Simulation results confirm that the performance of the proposed iterative detection outperforms conventional detection techniques. After a few iterations, bit-error-rate performance of the proposed receiver design is closely to the matched filter bound. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

CuZnS is a new promising material in thin film photovoltaics which is earth abundant and eco-friendly. Its electrical and optical properties can be controlled by varying atomic ratios of Copper and Zinc, so as to use it as absorber or window layers. Type of conductivity of this material can also be changed from n to p by adjusting Cu/Zn value. In the present work, we report improvement of cell parameters of CuZnS/In2S3 hetero junction considerably from our own earlier reported values just by increasing Cu to Zn ratio in CuZnS. Current density increased from 5.4 mA/cm2 to 10.7 mA/cm2, thereby enhancing conversion efficiency from 1% to 1.95%. Results are explained on the basis of improvement of multiple band structure. [ABSTRACT FROM AUTHOR]

Nanocrystalline oxygen-deficient ZnO thinfilm sensors were prepared by spray pyrolysis technique using zinc acetate dissolved in propanol and water as precursor. Response of the sensor to target gases NO2 and H2S is studied. At optimum temperature of 200.C, the sensors have a response of 3.32 to 7 ppm NO2 and 1.4 to 18 ppm of H2S gas. The analytical characterizations of the prepared sensors were performed using X-ray diffraction measurement, scanning electron microscopy, energy-dispersive X-ray spectroscopy and Raman spectroscopy. Dynamic response of sensors to different concentrations of NO2 and H2S gas was tested at optimum temperature. Experimental data revealed the sensors to be more selective to NO2 gas with satisfactory response and recovery time. [ABSTRACT FROM AUTHOR]

CuZnS is a promising material for solar cells, having mixed structure of CuxS and ZnS. In CuZnS thin films prepared by Chemical Spray Pyrolysis, it was observed that the material can be changed from n-type to p-type and electrical conductivity can be increased by 4 orders by just varying the Cu concentration. Increase in concentration of Cu also leads to decrease of band gap from 3.4 eV to 1.8 eV. Films of high concentration of Cu can be used as good absorber and Cu-poor films as buffer/window layer in solar cells. A bilayer heterojunction photovoltaic device could be fabricated using automated spray machine. Here, CuZnS was the absorber layer and In2S3 was the buffer layer. Using Ag as top electrode, J-V characteristics of the cell was recorded. For the optimum doped cell, the parameters obtained were Voc = 0.451 V, Jsc = 5.47 mA/cm², FF = 42.2%, and η = 1.04%. [ABSTRACT FROM AUTHOR]

The present work reports the influence of indium concentration and annealing temperature (100-400 °C) on the structural and optoelectronic properties of indium selenide thin films grown using a stack elemental layer technique. The concentration of indium in indium selenide thin films is varied by adjusting the thickness of the indium layer to 28, 42 or 56 nm while keeping the selenium layer thickness constant at 200 nm. Depending on the indium layer thickness of 42 or 56 nm, indium selenide thin films exhibited a phase transition either from a mixed phase (InSe, γ-In2Se3 and β-In2Se3) and/or from a complete amorphous phase to a single phase γ-In2Se3 at annealing temperature 400 or 300 °C, respectively, with a preferential grain orientation along the c-axis. Depth-wise X-ray photoelectron spectroscopy (XPS) analysis conducted on these samples (thickness of Se = 200 nm, In = 56 nm) showed evidence of a phase transition from amorphous to crystalline γ-In2Se3 phase and formation of uniform stoichiometric (In/Se = 40:60) indium selenide. On the other hand, indium selenide grown using an indium thickness of 28 nm did not exhibit any phase transition. While using X-ray diffraction (XRD) studies to analyse the structural properties, we made use of optical absorption and Raman spectroscopy in order to determine the optical energy gap and find the presence of parasitic β-In2Se3 phase, respectively. The growth along the c-axis either gives rise to carrier diffusion along the c-axis or causes the appearance of a higher photosensitivity (62-72) due to the absence of dangling bonds which trap photogenerated carriers. The properties exhibited by the c-axis-grown γ-In2Se3 suggest the potentiality of this material as a window layer in solar cell application. [ABSTRACT FROM AUTHOR]

This work projects photoluminescence (PL) as an alternative technique to estimate the order of resistivity of zinc oxide (ZnO) thin films. ZnO thin films, deposited using chemical spray pyrolysis (CSP) by varying the deposition parameters like solvent, spray rate, pH of precursor, and so forth, have been used for this study. Variation in the deposition conditions has tremendous impact on the luminescence properties as well as resistivity. Two emissions could be recorded for all samples--the near band edge emission (NBE) at 380 nm and the deep level emission (DLE) at ~500 nm which are competing in nature. It is observed that the ratio of intensities of DLE to NBE (IDLE/INBE) can be reduced by controlling oxygen incorporation in the sample. I-V measurements indicate that restricting oxygen incorporation reduces resistivity considerably. Variation of IDLE/INBE and resistivity for samples prepared under different deposition conditions is similar in nature. IDLE/INBE was always less than resistivity by an order for all samples. Thus from PL measurements alone, the order of resistivity of the samples can be estimated. [ABSTRACT FROM AUTHOR]

The origin of various defect levels in the SnS thin films deposited using chemical spray pyrolysis (CSP) technique has been explored in this manuscript, by employing low-temperature photoluminescence (PL) technique. Concentration of Sn in the samples was varied purposefully by ex situ diffusion in order to alter the defect levels. The acceptor level obtained at 0.22 eV from the Arrhenius plot, has been assigned as the defect level caused by the Sn vacancies present in the lattice. Two shallow donor levels are conclusively identified and their activation energies have been estimated. The present study could also unearth a trap level in the forbidden energy gap which was due to the oxygen contaminant occupied by the vacancy of Sn. This trap level could be removed by annealing the sample in vacuum or through the ex situ diffusion of Sn. Employing Kelvin probe force microscopy (KPFM), the work-function of SnS was obtained as 4.925 eV, from which the position of the Fermi level could be assigned. Based on the present work, an energy level scheme for SnS thin films is proposed outlying origin of various defect levels. [ABSTRACT FROM AUTHOR]

Polycrystalline CdTe thin films were irradiated with 80 MeV oxygen (O6+) ions for various fluences and its effect on the composition, structure, surface topography and optical properties have been investigated. The as-grown films are found to be slightly Te-rich in composition and there is no significant change in the composition after irradiation. X-ray diffraction analysis shows a high degree of crystallite orientation along the (111) plane of cubic phase CdTe. Upon irradiation a large decrease in intensity of the (111) plane and a small shift in the peak position has been resulted. The shift in the peak position is correlated with the change in the residual stress. The surface roughness of the films get increased after irradiation. A decrease in the grain size was observed after irradiation due to ion-induced recrystallization. The optical band gap energy decreased from 1.53 eV for as-grown film to 1.46 eV upon irradiation. The photoluminescence (PL) spectrum is dominated by the defect band and the effect of irradiation has been discussed and correlated with the observed change in the XRD peak position and optical band gap. [ABSTRACT FROM AUTHOR]

Indium sulfide (In2S3) films with three different thicknesses (150, 400 and 600 nm) were prepared using thermal evaporation at room temperature. As prepared samples were amorphous and subsequent annealing at higher temperature (>573 K) resulted in the formation of crystalline phase. Optical band gap was found in the range of 1.9–2.9 eV for as prepared samples and decreased with increase in annealing temperature. Interference fringe like structure in transmission spectra revealed that the films were fairly smooth and reflective. Variations in electrical resistivity and photosensitivity as a function of film thickness and annealing temperature were studied. X-ray Photoelectron Spectroscopic (XPS) studies clearly indicated uniform distribution of both indium and sulphur along the film. Energy Dispersive X-ray analysis showed that as prepared samples were stoichiometric. [ABSTRACT FROM AUTHOR]

Thermally Stimulated Conductivity (TSC) has been used to analyse defects in the novel material ß -In2S3. These films were deposited using spray pyrolysis technique, varying In:Sconcentration ratio in the spraying solution. TSC measurements allowed the study of electrical property and non-radiative transitions, due to the defects present in the material. TSC spectra revealed four defects with their prominence varying with In:Sconcentration ratio. Samples with lower In concentration showed the presence and prominence of indium vacancy. A chemical impurity level due to the presence of chlorine was also detected. Even though sulphur vacancy existed in all the samples irrespective of the variation of In:Sconcentration ratio its effect decreased with the increase of sulphur concentration. Another defect level was also detected from TSC measurements at high temperature that was attributed to the replacement of sulphur by oxygen which was maximum in films prepared from a spray solution of In:S= 2:3 and minimum for 2:8. This high temperature defect level acts as a neutral center while all the other three levels were seen to be coulomb repulsive. Results from XPS analysis are found to be in good agreement with the TSC results. [ABSTRACT FROM AUTHOR]

Copper indium sulfide thin films were prepared using copper diffusion into argon ion implanted In2S3 thin films. A comparative study of copper diffusion in pristine and ion implanted In2S3 samples was also performed. It was found that copper indium sulfide formation was much better in argon implanted samples compared to that in unimplanted samples. Copper diffusion in implanted samples enabled us to prepare an In2S3/CuInS2 solar cell. The fill factor of the cell prepared was 30.2% and the efficiency was 0.34%. [ABSTRACT FROM AUTHOR]

Optical absorption studies in β-In2S3 thin films of band gap 2.66 eV, prepared using chemical spray pyrolysis technique, revealed presence of a defect band which could assist absorption of sub band gap photons. Extrinsic photoconductivity under excitation of 2.33 eV was observed in these films. Photoluminescence studies revealed a green emission from the films providing a recombination path to these carriers. Temperature dependence of photoconductivity showed that the states in the defect band were continuously exchanging carriers with the conduction band which caused the photocurrent to show persistent photoconductivity. Temperature dependence of photocurrent revealed existence of shallow traps located ∼24 meV below the conduction band which played vital role in controlling the photosensitivity of the films. Temporal dependence of photoconductivity revealed decay tails which were identified to be the effect of thermal release of carriers form the shallow traps. [ABSTRACT FROM AUTHOR]