Investigation of doped cuprous halides for photovoltaic and display applications

The thesis mainly focuses on the growth and optoelectronic characterisation of the doped cuprous halides (CuX) with high UV/blue emission properties and the light harvesting in the CuBr/Si based heterojunction photovoltaic (PV) cells. Since cuprous halides are short wavelength emitters with high excitonic binding energies, growth of lower resistivity, highly luminescent p and n-type films are essential for the development of the future excitonic based light emitting devices with these materials. We describe the deposition and characterisation of the Zn doped n-type CuCl and oxygen doped p-type CuBr with higher carrier concentration using pulsed dc magnetron sputtering and thermal evaporation followed by oxygen plasma exposure, respectively. The structural and morphological properties of the n-type Zn doped CuCl films are investigated using XRD, SEM and AFM measurements. Our findings show that, the crystallinity of CuCl increases with doping of Zn and the maximum is obtained for the 3 % doped film, beyond which crystallinity decreases. The Zn doping has no deleterious impact on the structural and luminescent properties of CuCl up to a doping percentage of 5. An order of magnitude reduction in the resistivity of the CuCl films is obtained as a result of Zn doping. The resistivity, n-type carrier concentration and carrier mobility corresponding to the 3 % Zn doped films were, respectively 6 Ωcm, ~ 9.8×1018 cm-3 and 0.1 cm2V-1s-1. The influence of Zn doping on the electronic structure of CuCl is investigated using photoemission spectroscopic studies. Our studies on the Cu and Cl core level spectra show the presence of trace amounts of Cu2+ species in the undoped CuCl sample along with the major Cu+ species. This is verified by the observation of the satellite and shoulder peaks in the Cu 2p core level and a higher binding energy tail in the Cl 2p core level spectra. The disappearance of the cupric species with doping of Zn (3 %) is also observed. Furthermore, the shifting of the valence band towards the higher binding energy confirms the filling of the conduction band owing to the Zn doping, which explains the improvement of the conductivity of the doped films. vii We have successfully deposited p-type CuBr films by doping of oxygen. Our findings show that, there is no significant influence on the structural properties of the CuBr up to an oxygen plasma exposure time of 5 min. The investigation of the optical properties confirms good luminescence of the CuBr films up to a plasma exposure time of 3 min. The electrical characterisations of the oxygen plasma exposed films reveal that, oxygen act as a good acceptor for CuBr. The resistivity of the 3 min oxygen plasma exposed samples reduces to the order of ~ 1 Ωcm. SIMS analysis shows that, the diffusion of oxygen is quite good in the CuBr films. The realization of the heterojunction PV cell based on p-CuBr/n-Si is investigated. The I-V characteristics confirm the rectification behaviour of the p-n diode with a turn on voltage of ~ 1 V. The photoresponse properties of the heterojunction are studied by measuring the I-V characteristics under illumination. The photogenerated carrier formation is confirmed by the increased reverse current under illumination of the heterojunction. The wavelength dependence of the photo current was also studied using LED illumination. Development of ultrathin transparent Cr contacts, useful for the electroluminescent device fabrication was also discussed. This can be used as an alternative to well-known Indium Tin Oxide films for the future fabrication of the CuX-based display devices

The clinical study of vaginal birth after caesarean section

Background: VBAC has reduced the rate of repeat caesarean section in modern medicine. VBAC-TOL is successful in 60-80% of acceptable candidates if applied to all patients presenting with prior caesarean procedure (8.2-8.5%), there is potential to increase the overall vaginal delivery rate by 5%. Though the safety of VBAC in carefully selected patients have been demonstrated in several studies, controversy continues over when to advise patients who had caesarean section to undergo TOL. The purpose of current study was to know the success of VBAC, to know the maternal morbidity and mortality and foetal outcome in VBAC group.Methods: It was a prospective study performed on women with one previous LSCS admitted to tertiary care hospital for a period of one year from August 2018 to August 2019 at DM Waynad institute of medical sciences, Waynad.Results: In the present study 292 women with one previous LSCS were selected, among them 32 women had elective LSCS for various indications, 260 women underwent TOL. Among 260 women, 152 women achieved VBAC (58.46%) and 108 women underwent LSCS following failed TOL. Maternal morbidity was 9.61%. The incidence of scar dehiscence was 2.69% and uterine rupture was 0.38%. There was no maternal and foetal mortality in this study. NICU admission was 4.6%.Conclusions: Trial of labour should be encouraged in women with one previous LSCS with no obstetric complications

On Board Diagnostics (OBD) Scan Tool to Diagnose Emission Control System

Climate change has become very important issue the world is facing today. To control impact of climate change and improve quality of life, one of the key factor targeted is vehicular emissions. To control emissions very stringent emission norms are introduced by various government agencies across the world. This called for increased use for electronics in the engines and vehicles. This complicates the matter at service and manufacturers. The engine computer (Electronic Control Unit) with international protocol like OBD is used to control electronic parameters in engines. This review paper describes emission compliance requirement with brief introduction of the OBD system along with scan tool to diagnose the system

Formative Evaluation to Determine Facilitators and Barriers to Nurse-driven Implementation: Designing an Inpatient mHealth Intervention to Support Smoking Cessation

The inpatient setting is often a missed opportunity for the introduction of technology to promote health using behavioral techniques. Nurses are stakeholders in the implementation of technology for patients in the inpatient setting and are essential for the determination of feasibility and relevance. The objective of this study was to identify facilitators and barriers for introduction of health-related patient technology, and specifically the appropriateness of mobile health (mHealth) technology in the hospital setting as identified by nurse leaders and staff. Methods of formative evaluation included nurse leader and staff semi-structured interviews and qualitative analysis. Nurses are comfortable with patients using mHealth technology in the inpatient setting. Facilitators for the introduction of technology to hospitalized patients were identified. Based on the formative evaluation findings, we developed an Implementation Program for mHealth technology introduction in the inpatient setting

Hybrid Low Complex near Optimal Detector for Spatial Modulation

In our previous work maximum throughput in multi stream MIMO is analyzed by overcoming the inter antenna interference. To mitigate the Inter antenna interference spatial modulation can be used. Spatial Modulation(SM) aided MIMO systems are the emerging MIMO systems which are low complex and energy efficient. These systems additionally use spatial dimensions for transmitting information. In this paper a low complex detector based on matched filter is proposed for spatial modulation to achieve near maximum likelihood performance while avoiding exhaustive ML search since MF based detector exhibits a considerable reduced complexity since activated transmitting antenna and modulated amplitude phase modulation constellation are estimated separately. Simulation results show the performance of the proposed method with optimal ML detector, MRC and conventional matched filter methods

Comparison of Classification Algorithm for Crop Decision based on Environmental Factors using Machine Learning

Crop decision is a very complex process. In Agriculture it plays a vital role. Various biotic and abiotic factors affect this decision. Some crucial Environmental factors are Nitrogen Phosphorus, Potassium, pH, Temperature, Humidity, Rainfall. Machine Learning Algorithm can perfectly predict the crop necessary for this environmental condition. Various algorithms and model are used for this process such as feature selection, data cleaning, Training, and testing split etc. Algorithms such as Logistic regression, Decision Tree, Support vector machine, K- Nearest Neighbour, Navies Bayes, Random Forest. A comparison based on the accuracy parameter is presented in this paper along with various training and testing split for optimal choice of best algorithm. This comparison is done on two tools i.e., on Google collab using python and its libraries for implementation of Machine Learning Algorithm and WEKA which is a pre-processing tool to compare various algorithm of machine learning

Highly transparent and reproducible nanocrystalline ZnO and AZO thin films grown by room temperature pulsed-laser deposition on flexible zeonor plastic substrates

Zeonor plastics are highly versatile due to exceptional optical and mechanical properties which make them the choice material in many novel applications. For potential use in flexible transparent optoelectronic applications, we have investigated Zeonor plastics as flexible substrates for the deposition of highly transparent ZnO and AZO thin films. Films were prepared by pulsed laser deposition at room temperature in oxygen ambient pressures of 75, 150 and 300 mTorr. The growth rate, surface morphology, hydrophobicity and the structural, optical and electrical properties of as grown films with thicknesses∼65–420 nm were recorded for the three oxygen pressures. The growth rates were found to be highly linear both as a function of film thickness and oxygen pressure, indicating high reproducibility. All the films were optically smooth, hydrophobic and nanostructured with lateral grain shapes of∼150 nm wide. This was found compatible with the deposition of condensed nanoclusters, formed in the ablation plume, on a cold and amorphous substrate. Films were nanocrystalline (wurtzite structure), c-axis oriented, with average crystallite size∼22 nm for ZnO and∼16 nm for AZO. In-plane compressive stress values of 2–3 GPa for ZnO films and 0.5 GPa forAZO films were found. Films also displayed high transmission greater than 95% in some cases, in the 400–800 nmwavelength range. The low temperature photoluminescence spectra of all the ZnO and AZO films showed intense near band edge emission. A considerable spread from semi-insulating to n-type conductive was observed for the films, with resistivity∼103 Ω cm and Hall mobility in 4–14 cm2 V−1 s−1 range, showing marked dependences on film thickness and oxygen pressure. Applications in the fields of microfluidic devices and flexible electronics for these ZnO and AZO films are suggested

Indian Space Programme

Modern space science had its beginnings around 1946 when scientists started the deployment of instruments to the outer fringes of the earth’s atmosphere using balloons and rockets to study radiations from outer space as well as geophysical phenomena. In spite of the professed scientific goals for the first earth satellite missions, the launch of SPUTNIK on 4 October 1957 by the then Soviet Union added a new dimension to the cold war between the US and the Soviet Union. The early scientific satellite missions of the US also had implicit goals of pursuing US interest in establishing the International legal principle that national sovereignty did not extend to the altitudes at which the satellite would orbit. Thus there was no obstacle in International law to the overflight of a reconnaissance satellite over Soviet territory. Against this backdrop, it is significant to note that the early inspiration for the Indian Space Programme came not from any military objectives, but from the interests of a large scientific community who have been actively engaged in research programmes related to geophysics and astrophysics