Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Engineering

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 361 - 390 of 761

Full-Text Articles in Entire DC Network

Assessing The Influence Of Self-Efficacy On The Acceptance Of Mobile Phone Technology Within The Smes, Renatus Michael Mushi Jan 2020

Assessing The Influence Of Self-Efficacy On The Acceptance Of Mobile Phone Technology Within The Smes, Renatus Michael Mushi

Journal of International Technology and Information Management

Mobile phone technologies have proved to provide a significant transformation in performing various activities within companies, especially in least developed regions. Mobile phones provide opportunities for employees of organisations to work any time and anywhere. SMEs comprise of employees who perform multitasking job roles due to their small in size and low financial capabilities and most cases, some of them work remotely from their main offices.

Self-Efficacy is a belief that the user has enough skills to use technology to perform a task at hand. This is one of the factors influencing of acceptance of technologies at the workplaces such …


Methodology For Quantifying Resiliency Of Transportation Systems, Hannah Rose Russell Jan 2020

Methodology For Quantifying Resiliency Of Transportation Systems, Hannah Rose Russell

Doctoral Dissertations and Master's Theses

The National Science Foundation’s definition of resiliency is “the ability to prepare and plan for, absorb, recover from, or more successfully adapt to actual or potential adverse events” (National Science Foundation, 2016). While this definition is informative and useful, it lacks a quantitative reference. There is a need for a method of quantifying resilience to better plan and prepare for system wide disruptions. The research effort described herein provides a quantifiable measures of system resiliency, consistent with NSF’s definition. Fundamentally, a system disruption can be partitioned into five distinctive states: the stable pre-event state, the absorption state, the disrupted state, …


Integrated Mobile And Web-Based Application For Enhancing Delivery Of Hiv/Aids Healthcare Information In Tanzania, Ibrahim Mwammenywa Dec 2019

Integrated Mobile And Web-Based Application For Enhancing Delivery Of Hiv/Aids Healthcare Information In Tanzania, Ibrahim Mwammenywa

Tanzania Journal of Engineering and Technology (TJET)

This study aims to develop an integrated e-health platform for enhancing delivery of HIV/AIDS healthcare information in Tanzania, which consists of a mobile application and a web-based system. The study is based on the system's functional and non-functional requirements for an e-health system for delivery of HIV/AIDS healthcare information. The Rapid Application Development (RAD) model was adopted during the system development. The system requirements were modelled into Data Flow Diagram (DFD) in order to obtain the clear flow of the HIV/AIDS healthcare information between the clients and HIV/AIDS healthcare practitioners. With the use of different software development tools and environment …


Land Use/Cover Change And Their Impacts On Streamflow In Kikuletwa Catchment Of Pangani River Basin, Tanzania, Upendo Msovu Dec 2019

Land Use/Cover Change And Their Impacts On Streamflow In Kikuletwa Catchment Of Pangani River Basin, Tanzania, Upendo Msovu

Tanzania Journal of Engineering and Technology (TJET)

Streamflow perturbation is highly prevalent in Kikuletwa catchment. However, little is known concerning land use/cover change (LULCC) with regard to streamflow perturbation in the catchment. This study aims to detect the historical and predict future LULCC and assess their impacts on streamflow amounts using the Soil and Water Assessment Tool (SWAT) model. Supervised classification of Landsat imagery data for 1985, 2000 and 2015 years was done in ERDAS 14 Imagine software. Future prediction of LULCC was done using Module for Land Use Change Evaluation (MOLUSCE) tool, a QGIS plug-in. An accuracy ranging from 79% to 82% was obtained for all …


The Potentials Of Faecal Sludge Treatment Using Local Conditioners In Tanzania: A Review, Doglas Benjamin1 Dec 2019

The Potentials Of Faecal Sludge Treatment Using Local Conditioners In Tanzania: A Review, Doglas Benjamin1

Tanzania Journal of Engineering and Technology (TJET)

Worldwide, every day human beings generate millions of tons of Faecal Sludge (FS), which is rich in water, nutrients, energy, and organic compounds. Yet FS is not being managed in a way that permits us to derive value from its reuse, while at the same time, millions of farmers struggle with depleted soils and lack of water. In most of the developing countries, energy for cooking is mainly derived from cutting of trees, either as wood or charcoal. Resource recovery and reuse from FS can create livelihoods, enhance food security, support green economies, reduce waste and contribute to cost recovery …


Prediction Of Haul Units’ Requirements For The Open Pit Mines Operating Towards Closure, Bartłomiej Skawina Dec 2019

Prediction Of Haul Units’ Requirements For The Open Pit Mines Operating Towards Closure, Bartłomiej Skawina

Tanzania Journal of Engineering and Technology (TJET)

The determination of haul units is one of the important steps in the equipment selection process. The process should aim at minimizing the operational costs and create an optimal match for the haulage system. When open pit mines operating towards closure, reducing the operational costs results in significant gaining, and the savings can be used to implement some of the closure plans. In this paper, the prediction of haul units for an open pit mine which operates towards the final pit limit was analysed using discrete event simulation and multiple linear regressions. The result shows that the changes in production …


Practical Approach For Removal Of Natural Organic Matter And Defluoridation Of Maji Ya Chai River Water: Use Of Acid Pre-Treated Bone Char And Coagulants, Godfrey Mbabaye Dec 2019

Practical Approach For Removal Of Natural Organic Matter And Defluoridation Of Maji Ya Chai River Water: Use Of Acid Pre-Treated Bone Char And Coagulants, Godfrey Mbabaye

Tanzania Journal of Engineering and Technology (TJET)

The removal of natural organic matter (NOM) and fluoride from Maji ya Chai River water (MCRW) using bone char (BC) and coagulants was investigated. Fine BC particles ranging from 0.045 to 0.2 mm were used in a 1 litre half-filled container, stirred at 300 rpm for 60 min followed by addition of a commercial coagulant and allowed to settle for 24 hours to remove NOM. MCRW practicable and affordable defluoridation method for removal of NOM through defluoridation with BC pre-treated with 0.3 N HCl followed by coagulation with Poly-aluminium chloride (PACl) is proposed. Reduction of fluoride from 21 mg/L to …


Reviewing The Potential And Constraints Of Modified Technology Options For Faecal Sludge Management In Dar Es Salaam, Tanzania, Amour Seleman Dec 2019

Reviewing The Potential And Constraints Of Modified Technology Options For Faecal Sludge Management In Dar Es Salaam, Tanzania, Amour Seleman

Tanzania Journal of Engineering and Technology (TJET)

Cities in the developing world face the challenge of safe management of faecal sludge because of rapid population growth that overwhelms the sanitation infrastructure and services. In developing countries, only 50% of faecal sludge (FS) generated is safely managed the remaining portion is haphazardly disposed of in the environment risking public health and environment. In response to the urgent need for safely managed sanitation services, technological options for containment, desludging and transportation of FS are being modified. This paper reviewed current desludging practices and the potential of modified technological options for addressing FSM at containment, desludging, and transportation in Dar …


Blind Algorithm Development For Peak To Average Power Ratio Reduction In Ofdm Systems Under Frequency Selective Channels, Kwame S. Ibwe Dec 2019

Blind Algorithm Development For Peak To Average Power Ratio Reduction In Ofdm Systems Under Frequency Selective Channels, Kwame S. Ibwe

Tanzania Journal of Engineering and Technology (TJET)

One major drawback of orthogonal frequency division multiplexing (OFDM) system is peak to average power ratio (PAPR). This effect causes high power amplifier (HPA) to introduce intermodulation and out of band radiation as the signal goes through, thus degrades the performance of OFDM systems. This paper proposes blind algorithms which takes advantage of signal transformation technique and signal distortion technique. Simulation results show that at complementary cumulative distribution function (CCDF) level of 10-3, the proposed algorithm achieved 3.2 dB PAPR improvement compared to discrete Fourier transform with interleaved frequency division multiple access (DFT-IFDMA) based algorithm. The bit error rate (BER) …


Target-To-Target Interaction In Through-The-Wall Radars Under Path Loss Compensated Multipath Exploitation-Based Signal Model For Sparse Image Reconstruction, Emmanuel K. Kokumo, Baraka Maiseli, Abdi T. Abdalla Dec 2019

Target-To-Target Interaction In Through-The-Wall Radars Under Path Loss Compensated Multipath Exploitation-Based Signal Model For Sparse Image Reconstruction, Emmanuel K. Kokumo, Baraka Maiseli, Abdi T. Abdalla

Tanzania Journal of Science

Multipath caused by reflections from interior walls of buildings has been a long-standing challenge that affects through-the-wall radar imaging. Multipath creates ghost images that introduce confusion when detecting desired targets. Traditionally, multipath exploitation techniques under the compressive sensing framework have widely been applied to address the challenge. However, the multipath component emanating from target-to-target interactions has not been considered–a consequence that may, under multiple target scenarios, lead to incorrect image interpretation. Besides, far targets experience more attenuation due to free space path loss, hence resulting into target undetectability. This study proposes a signal model, based on multipath exploitation techniques, by …


Cal Poly Construction Management Student’S Main Determinants For Potential Employment Opportunities: A Guide For Employers, David Joseph Van Buskirk Ii Dec 2019

Cal Poly Construction Management Student’S Main Determinants For Potential Employment Opportunities: A Guide For Employers, David Joseph Van Buskirk Ii

Construction Management

California Polytechnic State University’s Construction Management department has an excellent reputation. This reputation, boosted by a 100% placement rate, attracts an abundant number of recruiters, a number that continues to grow every year. With the large number of recruiters coming to campus, students often find themselves in the fortunate situation of having multiple offers and having the opportunity to select amongst various companies. To be competitive, employers would best serve to cater their recruitment process to suit the needs of the students they are trying to hire. While plenty of research has been conducted to investigate and determine how recruiters …


Microstructure And Materials Characterization Of Sol-Gel Synthesized Zro2 Systems, Sungsoo Park, Godlisten Shao Aug 2019

Microstructure And Materials Characterization Of Sol-Gel Synthesized Zro2 Systems, Sungsoo Park, Godlisten Shao

Tanzania Journal of Science

The roles of pH and thermal treatment on the microstructures of sol-gel synthesized mesoporous ZrO2 systems have been investigated. In order to control the crystal structures and particle sizes of the final products, the pH values of the reaction mixtures were controlled between 5 and 12 followed by calcination at temperatures ranging from 450 to 1000 °C. The microstructures of the zirconia systems were then examined by XRD, TEM, TGA, UV-visible DRS and nitrogen physisorption study analyses. It was found that pH values and calcination temperatures have significant influence on the crystallization temperature, phase transformation and particle size of the …


The Comparative Analysis Of The Performances Of Four And Six Pole Pairs Permanent Magnet Synchronous Generator, Ra Msuya Jun 2019

The Comparative Analysis Of The Performances Of Four And Six Pole Pairs Permanent Magnet Synchronous Generator, Ra Msuya

Tanzania Journal of Engineering and Technology (TJET)

Wind power applications using multi-poles permanent magnet generators have become very attractive especially in small ratings. Low-speed multi-pole PM generators are maintenance-free and may be used in different climate conditions. Most of the low speed wind turbine generators presented is permanent magnet machines, which have advantages of high efficiency and reliability since there is no need of external excitation and conductor losses are removed from the rotor. From the study two types of PM AC generator are designed with 6 pole pairs and the other one with 4 pole pairs. These generators were designed and analysed using Maxwell software. The …


Linking Quality Management Practices With Performance Of Manufacturing Industries In Tanzania, Mussa Iddi Mgwatu Dr. Jun 2019

Linking Quality Management Practices With Performance Of Manufacturing Industries In Tanzania, Mussa Iddi Mgwatu Dr.

Tanzania Journal of Engineering and Technology (TJET)

Local products of manufacturing industries in Tanzania are subjected to intense competition in the markets. Product quality is one of key factors that play a considerable role for manufacturing industries to win the competitive advantage. This paper attempts to analyse the extents of quality management practices (QMP) and manufacturing performance (MP) as well as to examine the linkage between practices and performance. Data was collected from seventy-eight (78) manufacturing industries in Dar es Salaam region using questionnaires comprising of both single-item and multi-item questions. Descriptive statistics was used to quantify the extent of quality management practices and manufacturing performance (MP) …


Influence Of Tempering And Cryogenic Treatment On Retained Austenite And Residual Stresses In Carbonitrided 18crnimo7-6 Low Alloy Steel, Richard Katemi Jun 2019

Influence Of Tempering And Cryogenic Treatment On Retained Austenite And Residual Stresses In Carbonitrided 18crnimo7-6 Low Alloy Steel, Richard Katemi

Tanzania Journal of Engineering and Technology (TJET)

This work investigated the influence of tempering conditions coupled with cryogenic treatment on thermal stabilization of retained austenite and residual stress distributions in carbonitrided 18CrNiMo76 low alloy steel samples. The carbonitriding conditions were set to enable attaining surface carbon and nitrogen content of 0.87 and 0.34 mass.-percent respectively. After carbonitriding, some of the samples were subjected to varying tempering conditions followed by cryogenic treatment at-120 °C using nitrogen gas. Analysis of both retained austenite and residual stresses was conducted using X-ray diffraction. In the as-quenched state, carbonitrided samples contained 52 mass.-percent. Samples that were directly subjected to the cryogenic treatment …


Development Of Improved Characteristic Equations For Lake Rukwa In Tanzania, Patrick Valimba Dr Jun 2019

Development Of Improved Characteristic Equations For Lake Rukwa In Tanzania, Patrick Valimba Dr

Tanzania Journal of Engineering and Technology (TJET)

Often Lake Rukwa characteristics have been misreported in literature giving different volumes and surface areas at similar water surface elevations. This study aimed at establishing reliable lake characteristics elevation-area-storage equations for Lake Rukwa by utilising all available data and information to define the bathymetry and derive characteristic equations. A procedure was developed that combines historical lake extents, spot heights from topographical maps and surveyed lake bathymetry to define refined bathymetry to levels it has never reached. It combined spot heights around the lake and selected 13,934 surveyed points (from 107,938 available) within the lake confined by the 820 m land …


Potential Use Of High Rate Algae Ponds For Resource Recovery In The Water-Food-Energy Nexus For Tanzania: A Review, Mary Kayombo Jun 2019

Potential Use Of High Rate Algae Ponds For Resource Recovery In The Water-Food-Energy Nexus For Tanzania: A Review, Mary Kayombo

Tanzania Journal of Engineering and Technology (TJET)

The use of High Rate Algal Ponds (HRAPs) for the treatment of wastewater and resource recovery has raised interest in recent years. Treatment of wastewater through this technology has proved to have high efficiency in reducing the level of pollution, nutrients, dissolved solids as well as pathogens. HRAPs are more efficient than conventional Wastewater Stabilization Ponds (WSPs) due to their design approach that provides room for high rate bio-chemical processes, which increase the mechanisms of nutrients and pathogens removal as well as the rate of micro-algae production for purposes of resource recovery. This paper reviews the upgrading potential of existing …


Research Methodology Adopted In Developing Tansse-L System, Ellen Kalinga Jun 2019

Research Methodology Adopted In Developing Tansse-L System, Ellen Kalinga

Tanzania Journal of Engineering and Technology (TJET)

Research methodology is among the very important part in a research work. It is the heart which describe the activities necessary for the completion of the research work. Research methodology provides a plan of investigation considered to obtain answers to research problems and it depends on the context of application. This paper presents the research methodology adopted when developing Tanzania Secondary Schools e-Learning (TanSSe-L) system, a learning management system (LMS) which was successfully developed through customization of Moodle open source LMS. TanSSe-L system is a context centered platform for secondary schools in Tanzania. TanSSe-L system was developed using a number …


Experimental Study On The Effect Of Moisture On Bolt Embedment And Connection Loaded Parallel To Grain For Timber Structures, Henry Meleki Kiwelu Jun 2019

Experimental Study On The Effect Of Moisture On Bolt Embedment And Connection Loaded Parallel To Grain For Timber Structures, Henry Meleki Kiwelu

Tanzania Journal of Engineering and Technology (TJET)

Connections are critical parts of timber structures, transmitting static and dynamic forces between structural elements. The ultimate behaviour of a building depends strongly on the structural configuration and the capacity of its connections. The complete collapse of a building or other less extensive accidents that may occur usually start as a local failure inside or in the vicinity of a joint. The main aim of this study has been to investigate if the short-term capacity of steel-wood dowel joints loaded parallel to the grain is affected by variations in moisture content associated with post fabrication drying or wetting of the …


Nonlinear Direct Torque Control Of Interior Permanent Magnet Synchronous Motor Drive, Jackson Justo Jun 2019

Nonlinear Direct Torque Control Of Interior Permanent Magnet Synchronous Motor Drive, Jackson Justo

Tanzania Journal of Engineering and Technology (TJET)

This paper presents a nonlinear direct torque control (NDTC) strategy of interior permanent magnet synchronous motors (IPMSMs) for electric vehicle (EV) propulsion. The proposed NDTC scheme applies a nonlinear model of IPMSM to dynamically determine the optimal switching states that optimize the EV drivers’ decision to reduce the workload. Moreover, the proposed NDTC method has a simple control structure and can explicitly handle system constraints and nonlinearities. The performance evaluation is conducted via a prototype IPMSM test-bed with a TMS320F28335 DSP. Comparative experimental results provide the evidence of improvements of the proposed NDTC strategy over the conventional DTC strategy by …


Material Flow Analysis As A Decision Supporting Tool For Faecal Sludge Resource Recovery: Mathematical Formulation And Quantification, Isabela Thomas Mkude Jun 2019

Material Flow Analysis As A Decision Supporting Tool For Faecal Sludge Resource Recovery: Mathematical Formulation And Quantification, Isabela Thomas Mkude

Tanzania Journal of Engineering and Technology (TJET)

In this work, a conceptual framework for faecal sludge (FS) management and resource recovery in Dar es Salaam city was developed. Material Flow Analysis (MFA) approach was used to assess and quantify the current materials and nutrients to support on decisions for nutrient recovery and minimize environmental pollution in three unplanned settlements of Manzese, Keko and Kipawa in Dar es Salaam city. Nitrogen and Phosphorus were chosen as indicators for the evaluation of the process. The results showed that about 75% of the Dar es Salaam city population relies on pit latrines and 15% connected to septic tanks, translating to …


Assessment Of Surface Water Resources In Great Ruaha River Sub-Basin Tanzania: Application Of Weap Model For Water Allocation And Utilization Impacts Analysis, Deogratias Mulungu Jun 2019

Assessment Of Surface Water Resources In Great Ruaha River Sub-Basin Tanzania: Application Of Weap Model For Water Allocation And Utilization Impacts Analysis, Deogratias Mulungu

Tanzania Journal of Engineering and Technology (TJET)

The Great Ruaha River (GRR) sub-basin is one of the most important waterways in Tanzania as it supports important economic activities. The sub-basin is progressively faced with an inevitable situation of increasing water demand among competing users while the quantity and quality of water is diminishing. The focus of this study was to assess allocation of existing (2012) and future (up to 2025) quantities of surface water in the GRR sub-basin with consideration of priorities given in the Tanzania Water Resources Management Act, 2009 in the order: domestic, environment, agriculture, livestock and non-domestic. Simulation of water allocation scenarios of irrigation …


A Decision-Making Framework For Hybrid Resource Recovery Oriented Wastewater Systems, Nader Rezaei Jun 2019

A Decision-Making Framework For Hybrid Resource Recovery Oriented Wastewater Systems, Nader Rezaei

USF Tampa Graduate Theses and Dissertations

Water shortage, water contamination, and the emerging challenges in sustainable water resources management (e.g., the likely impacts of climate change and population growth) necessitate adopting a reverse logistics approach, which is the process of moving wastewater from its typical final destination back to the water supply chain for reuse purposes. This practice not only reduces the negative impacts of wastewater on the environment, but also provides an alternative to withdrawal from natural water resources, forming a closed-loop water supply chain. However, the design of such a supply chain requires an appropriate sustainability assessment, which simultaneously accounts for economic, environmental, and …


Data Visualization Of Treatment Outcomes For Tuberculosis Patients, Joy Jenkins May 2019

Data Visualization Of Treatment Outcomes For Tuberculosis Patients, Joy Jenkins

Industrial Engineering Undergraduate Honors Theses

Tuberculosis is an infectious disease, and different treatments have been discovered over the years. However, patients may develop various drug resistance levels that affect the likelihood of becoming cured or dying. In this study, we sought to employ data visualization to explore the relationship between treatment trajectory, as indicated by smear and culture results in the follow-up tests and patient outcomes. A large sample of patients have been broken down by demographics including age, gender, and drug resistance status. Sankey diagrams were used to visualize the pathway progression of the patients over time split between two time periods- months 0-6 …


Modeling Driver-Pedestrian-Infrastructure Interactions At Signalized Midblock Crosswalks, Boniphace Kutela May 2019

Modeling Driver-Pedestrian-Infrastructure Interactions At Signalized Midblock Crosswalks, Boniphace Kutela

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cities and metropolitan areas are increasingly facilitating pedestrians’ movement by the provision of pedestrian walking facilities. As pedestrian traffic increases, the risk of crash involvement increases, especially at midblock locations, where pedestrians are exposed to unsafe interactions with vehicular traffic. To improve pedestrians’ safety at midblock locations, various countermeasures are provided, which include signalized crosswalks. Several studies have analyzed driver-pedestrian interactions, as well as pedestrian-infrastructure interactions at signalized midblock crosswalks. However, more in-depth studies are necessary, due to shortfalls of study assumptions, which have led to the application of improper statistical models, as seen in the literature. Improved models are …


3d Printing In Low Resource Healthcare Settings: Analysis Of Potential Implementations, Alenna Beroza Jan 2019

3d Printing In Low Resource Healthcare Settings: Analysis Of Potential Implementations, Alenna Beroza

Dissertations, Master's Theses and Master's Reports

3D printing has gained significant momentum in the past ten years, and its unique advantages make it especially ideal for use in low resource healthcare settings, where many designs have already been successfully implemented. Yet, little has been studied on how 3D printing can be sustainably and functionally implemented in low resource healthcare systems as a manufacturing practice. In this report, three business models are proposed for this implementation: In-House Operator, Independent Operator, and Print Farm. These models were then tested over four months in Kisumu county, Kenya, at two workshops and seven public hospitals. I worked with local medical …


Effects Of Aluminium And Tungsten Co-Doping On The Optical Properties Of Vo2 Based Thin Films, Cephas J Lyobha, Nuru R Mlyuka, Margaret E Samiji Dec 2018

Effects Of Aluminium And Tungsten Co-Doping On The Optical Properties Of Vo2 Based Thin Films, Cephas J Lyobha, Nuru R Mlyuka, Margaret E Samiji

Tanzania Journal of Science

Aluminium and tungsten co-doped vanadium dioxide (VO2:W:Al) thin films were deposited by DC reactive magnetron sputtering technique. In this work we report on the effects of aluminium and tungsten co–doping on the optical properties of vanadium dioxide (VO2) based thin films with a view of combining both increased luminous transmittance (Tlum) and lowered transition temperature (τc). The effect of aluminium and tungsten co-doping on semiconductor-metal transition of vanadium dioxide films was investigated and compared with tungsten doped and undopedVO2films. Spectral transmittances of the films were obtained using Shimadzu SolidSpec-3700 DUV UV-VIS-NIR spectrophotometer. The results revealed that the transmittance of tungsten …


Hall Effect Parameters Of Aluminium And Tungsten Co-Doped Vo2 Thin Films, Mohamed Mussa, Nuru R Mlyuka, Margaret E Samiji Dec 2018

Hall Effect Parameters Of Aluminium And Tungsten Co-Doped Vo2 Thin Films, Mohamed Mussa, Nuru R Mlyuka, Margaret E Samiji

Tanzania Journal of Science

The Hall Effect parameters of Al and W co-doped VO2 thin films were studied in order to explain the effect of co-doping on the electrical properties of thermochromic VO2 films. The carrier concentrations and conductivity of the films were found to increase with increase in temperature while carrier mobility decreased reaching a minimum around the transition temperature then slightly rose and became stable at high temperatures. Tungsten doped films displayed higher carrier concentrations and conductivity on both sides of the metal insulator transition and lower mobility compared to undoped and Al and W co-doped VO2 thin films.


Optimization Of Zinc To Tin Ratio In A Sol Gel Precursor Solution On The Growth And Properties Of Annealed Czts Thin Films, Justine John Tibaijuka, Margaret E Samiji, Nuru R Mlyuka Dec 2018

Optimization Of Zinc To Tin Ratio In A Sol Gel Precursor Solution On The Growth And Properties Of Annealed Czts Thin Films, Justine John Tibaijuka, Margaret E Samiji, Nuru R Mlyuka

Tanzania Journal of Science

CZTS thin films were deposited by sol–gel spin coating method using precursor solutions prepared by dissolving copper acetate dihydrate, zinc acetate dihydrate, tin chloride and thiourea in methanol and monoethylamine then annealed in RTP furnace at 500 °C. Sol–gel precursor solutions were prepared with different Zn/Sn in a precursor solution and were annealed at different time intervals; and their effects on the optical and electrical properties of CZTS (Cu2ZnSnS4) films were investigated. The optical band-gap values were estimated to be between 1.30 and 1.88 eV while the absorption coefficients were in the range of 104 cm–1 in the visible region. …


Compositional And Thickness Effects On The Optical Properties Of Zinc–Doped Selenium–Antimony Thin Films, Austine A Mulama, Julius M Mwabora, Andrew O Oduor, Cosmas M Muiva Dec 2018

Compositional And Thickness Effects On The Optical Properties Of Zinc–Doped Selenium–Antimony Thin Films, Austine A Mulama, Julius M Mwabora, Andrew O Oduor, Cosmas M Muiva

Tanzania Journal of Science

Chalcogenide system of antimony (Sb)-selenium (Se)-zinc (Zn) system is a promising semiconductor for phase change memory devices due to its thermal stability and low power consumption. The study investigated the effect of film thickness and zinc content on the optical properties of thermally evaporated Sb10Se90-xZnx (x = 0, 5, 10 & 15 at. %) thin films. It was found that transmittance (T~ 85-40%) and optical band gap energy (Eopt ~ 1.60 eV – 1.22 eV) decreased but absorption coefficient (α~0.840–2.031 104 cm–1) increased with increase in zinc content. Furthermore, as the film thickness increased from 53 ± 5 nm to …