Modeling a Bandwidth of a Two-Level Independent Quantum Laser System States

An electromagnetic radiation is basically considered to be a transverse wave propagating through an accessible media whether it is an optical fibre or a thin film depending on its propagating conditions. In analyzing its propagation, utilized specific cross-section areas have become an important base of understanding its extinction parameters. The term cross-section in this work applies only to boundary conditions within which particles interact within electromagnetic spectra through absorption or scattering. In such small volume contextual framework, nanotechnology reconsiders scattering cross-section coefficients. In this work, two different degenerate states were modeled and analyzed using a developed model of a laser cavity containing a media of length, L, with a gain of, k, per unit length which were mirrored to represent the upper and a lower level manifolds inhomogeneous broadening Stark levels respectively. The model developed created an impression that a laser medium is a coherent ensemble of particles or atoms whose bandwidth depends on how a laser is constructed

Effect of Surface Passivation on CdxNi1-xS Thin Films Embedded with Nickel Nanoparticles

Certain treatments done to binary CdS, such as incorporating Ni onto CdS produces ternary thin films may cause major optical parameters that have a number of applications including for solar cell device fabrication. In this paper, we report on the effect of surface passivation on the band gap and other related optical properties of CdNiS thin films. Thin films for CdxNi1-xS were prepared on glass substrates by chemical solution method. Effects of surface passivation and variation of the volume of nickel ions on the optical properties CdS hence obtaining CdxNi1-xS thin films was investigated. It was observed that the thin films hard an average Transmittance above 68 %, with reflectance below 25 % across UV-VIS-NIR region. A plot of (αhν) 2 versus hν gave energy band gap between 2.55–3.49 eV for as-grown samples and 2.82–3.50 eV for annealed samples. The passivated samples had band gap energy values within the range 2.85–3.12 eV. It was concluded that an increase in concentration of Cd2+ and Ni2+ ions in the reaction led to an increase the band gap while optical conductivity ranged between 3.78x1011–2.40x1012 S-1

Transmittance and Extinction Coefficient of Sea and Well-Water in Mombasa County, Kenya

Using a laser transmitter in the range of 200 nm to 1200 nm, transmittance and total extinction coefficients were determined for two different but close related optical media which are ocean water and shallow well water in Mombasa County, in Kenya. The results were interpreted using Lambert–Beer’s law as applied for very small ranges of concentrations. It was established that the total extinction coefficients for two forms of water showed linearity with values of total extinction coefficients found to be µt = 7.734 (g/ml)-1 mm-1 and µt = 127.6 mm-1 at a wavelength of 638 nm for ocean water and shallow well water respectively

TiO2 Thin Films by Solution Technique for Solar Cells

Titanium dioxide has a number of applications in solar cells. In this study, TiO2 thin films were synthesized using a simple but less expensive, low temperature and large area deposition method referred to as chemical bath deposition. Their electrical and optical properties were examined at various temperatures where it was observed that the films exhibited low reflectance which increased with increase in wavelength with refractive indices of 2.2–2.5 in the visible spectra. Sheet resistivity ranged between 13.54±0.095 Ω/m to 17.27±0.209 Ω/m. They were use to fabricate photovoltaic cell which exhibited the following parameters: a short circuit current, Isc=0.002445 A, open voltage, Voc = 0.04731 V, a fill factor, FF=0.551 and an efficiency, η=0.531 %. They were recommended for diode applications

Studies on Cd1Se0.6Te0.4 Thin Films by Spectroscopic and Diffractometer Characterization

Cadmium selenide tellurium is a compound containing cadmium, tellurium and selenium elements forming a combined solid. Hall measurements suggest that it is an n-type semiconductor. Related optical studies indicate that is transparent to infra-red radiation. Structural studies clearly show that it has a wurtzite, sphalerite crystalline forms. Cadmium is a toxic heavy metal, and selenium is only toxic in large amounts or doses. By this toxicity, cadmium selenide is a known to be carcinogen to humans; however, this does not stop investigating it for optoelectronic applications. Current research has narrowed down to investigating cadmium selenide when in the form of nanoparticles. Cadmium selenide finds applications has found applications in opto-electronic devices like laser diodes, biomedical imaging, nano-sensing, high-efficiency solar cells and thin-film transistors. By chemical bath deposition, Cd1Se0.6Te0.4 thin films were grown onto glass. Tellurium was gradually introduced as an impurity and its crystalline structure and optical properties were investigated by XRD and UV-VIS spectroscopy. The main Cd1Se0.6Te0.4/glass characteristics were correlated with the conditions of growing and post-growth treatment and it was found out that films were homogeneous films with controllable thickness onto the glass substrate and suitable for n-type “sandwich” heterostructures applications. Comparison of the intensities of equivalent reflexions provided a test for the internal consistency of the measurements. Equivalent reflexions in two specimens differed on average by 1.4 % and 0.6 % from the mean measured intensity, attesting to the high internal consistency of measurements from extended-face crystals. By comparison from data obtained from all samples showed their average deviation from the mean to be 0.9 %

Impact of Annealing Thin Films In(OH)xSy Growth By Solution Technique

Indium Hydroxy Sulphide has demonstrated abundance in resources, low prices, nontoxic characteristics, radiation resistance, high temperature resistance, and chemical stability, and therefore it has become an extremely important photoelectric, photovoltaic, and light sensing thin film material. Some treatment on this material include thermal annealing which is a process used for intrinsic stress liberation, structural improving, and surface roughness to control its electro-optical properties. In a qualitative way, annealing modifies surface morphology, intrinsic parameters, and electron mobility with temperature and time. In this work, an explanation on the surface modification of In(OH)xSythin films when subjected to an annealing process is discussed. Both electrical and optical effects caused by annealing were carried out and characterizations were performed at different annealing temperatures in nitrogen in the temperature range 373–573 K. Using optical measurements data and simulated data, Scout software was employed and the results showed that increasing annealing temperature causes a slight decrease in transmittance with a consequence of modifying the energy band gaps values between 2.79–3.32 eV. It was concluded that annealing influence optical transmittance and resistance of the film make the thin films potential for photovoltaic, and light sensing applications

Electrical Behavior of Cd0.3Zn1.1x S0.7 Thin Films for Non-Heat Light Emitting Diodes

In developing countries like Kenya, solution processing technique is the cheapest and simplest technique to grow inorganic composites thin films. This method was used to grow thin films of Cd0.3Zn1.1xS0.7on ordinary microscope Perspex substrate slides from aqueous solutions of Zinc chloride and cadmium chloride in ammonia solution. A solution of triethanalomine was used as a complexing agent while thiourea was used as source of sulphide ions. Electrical properties as a function of their thicknesses were obtained by varying deposition time while all other parameters were maintained constant. Using a resistance measurement device and a Gauss meter, resistivity and the conductivity of the films were found to be thickness dependent with semiconductor nature

Influence of Different Spherical Binary Plasmonic NPs on HTM Layer in Methyl Ammonium Lead Triiodide Solar Cell

Methylammonium lead triiodide perovskite solar cells have attracted huge research interest. Its optoelectronic properties are competing with those of silicon wafers. It is a hybrid absorber with a direct band gap of about 1.53 eV with good light-absorption capability appropriate for optoelectronic applications. A typical perovskite solar cell HTML layer rarely incorporates ZnO or Cu2O or TiO2 nanoparticles to increase charge carrier transport. These ZnO, Cu2O, TiO2 nanoparticles can be introduced into the HTM layer to modify its PSCs efficiency and performance. These nanoparticles are direct band gap binary semiconductors with a wide band gap energy range of 2.17 eV to 3.37 eV respectively which can lead to higher transport mobility and enhanced HTM nanostructured layer. In this paper, two model solar cell having a ITO/TiO2/CH3NH3PbI3/P3HT/Ag and ITO/TiO2/Ag:CH3NH3PbI3/P3HT/Ag structures were proposed, geometrically modelled  and simulated using SCAPS-1D software. Their HTM layer (composed of P3HT) was doped with ZnO, Cu2O, and TiO2 nanoparticles respectively to determine their influence on PCEs of this solar cells. It was revealed that starting from undoped P3HT layer all through the Cu2O, ZnO to TIO2 doped layers, efficiency reduced from 13.123 % and 9.071% respectively; fill factor (FF) also reduced from 69.4% to 48.9 % for the doped CH3NH3PbI3 perovskite solar cell while efficiency of doped CH3NH3PbI3 perovskite solar cell reduced from 13.033 % and 9.091%, the fill factor (FF) also reduced from 66.4% to 52.9 % respectively. It was noted that the solar cell employing P3HT undoped layer had the best performance and concluded that introducing nanoparticles onto P3HT layer has a negative impact on the performance of CH3NH3PbI3 perovskite solar cell

Narrow Band Gap Ternary Absorber Layer for Solar Cell for Small Business Enterprises in Equatorial Africa

According to recent studies, on the Daily nation newspaper, in Kenya of 6th January 2017 featured the story, the number of people doing the same thing in surrounding villages was so high that many of them had to leave their phones behind at the charging centre (for up to three days) before returning to pick them. To fight darkness, up to 80 percent of Africans depend on personal generators, candles and kerosene (paraffin) lamps to provide basic lighting. Let’s not even talk about all the other things we desperately need electricity for – iron clothes, pump water, charge mobile phones etc. In this article, we shall focus on the types of solar cell materials that can be used to fabricate solar cell to be installed on roof tops to generate electricity used by individuals and households. Photovoltaic devices are used to convert solar radiation energy into electrical forms of energy for various uses. Current research is geared towards using thin films with wide band gaps to allow optimum penetration of radiation within the VIS - NIR region. Inorganic wide band gap, CdxZn1-xS thin films and narrow band gap, PbS thin films were optimized through chemical solution technique in this study. Wide band gap thin films of CdxZn1-xS were grown at about 820C while those of narrow band gap thin films of PbS were grown at room temperature utilizing aqueous conditions. Their optical constants were investigated and found to be suitable for solar cells applications. &nbsp

Effects of Quantum Confinements in Tin Sulphide Nanocrystals Produced by Wet-Solution Technique

In thin film nano-crystals studies, electron energy levels are known not continuous in the bulk thin films but are rather discrete(finite density of states) because of confinement of their electron wave functions to the physically dimensions of the particles. This phenomenon is called Quantum confinement and therefore nano-crystals are also referred to Quantum dots. The quantum confinement effect is mainly observed when the size of the particle involved is too small to be comparable to the wavelength of the electron. To understand this effect, this study broke the words confinement to mean to confine the motion of randomly moving electron to restrict its motion in specific energy levels (discreteness) and the term quantum to reflect the atomic realm of particles involved in this study. So as the size of a particle decrease to a nano scale, then the decrease in confining dimension causes the particle energy levels to be too discrete and at the same time widens up the band gap. As a result the ultimately effect is that the band gap energy increases. In this study, nanocrystalline tin sulphide (SnS) powder was prepared using tin chloride (SnCl2) as a tin ion (Sn+2) source and sodium sulfide (Na2S) as a sulfur (S-2) ion source using solution magneto DC sputtering technique. The as-synthesized thin film in form of nanoparticles were then qualitatively and quantitatively analyzed and characterized in terms of their morphological, structural and optical properties and found to have an orthorhombic structure whose direct band gap had blue shifted (1.74 eV) and was confirmed using theoretical calculations of exciton energy based on the potential morphing method (PMM) in the Hartree Fock approximation