Physics
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Item Electrodeposited thin film SnO2 photoelectrode for PEC applications(Institute of Physics, Sri Lanka, 2024) Kafi, F.S.B.; Gunaratna, B.H.; Jayathilaka, K.M.D.C.; Wijesundera, R.P.Tin oxide (SnO2) is a promising semiconductor material to develop photoelectrodes for photoelectrochemical (PEC) cells. Indeed, an effective PEC cell could be developed only if the photoelectrode is stable and free of corrosion in the selected electrolytic solution. In other words, the choice of an electrolyte for a PEC cell determines the stability of the photoelectrode in the PEC cell. In this study, we propose aqueous 0.1 M sodium nitrate (NaNO3) as an effective electrolyte for the PEC cell where thin film SnO2 is a photoelectrode. Current-voltage (I-V) measurements obtained by illuminated chopped ultra violate (UV) radiation established the electrodeposited thin films of SnO2 are stable and free of corrosion/photocorrosion in our PEC cell. In addition, we report the dependence of the photoresponses of electrodeposited thin film SnO2 in this PEC on the bath temperature and the deposition time.Item Effect of pre-surface treatments on p-Cu2O/Au Schottky junctions(Journal of the National Science Foundation of Sri Lanka,, 2021) Kafi, F.S.B.; Jayathilaka, K.M.D.C.; Wijesundera, R.P.; Siripala, W.Cuprous oxide (Cu2O) is a suitable semiconducting material in fabrication for low-cost, eco-friendly semiconductor junction devices. Besides the parameterization of the growth conditions of Cu2O, formation of metal contacts impact the overall performance of these type of devices. The existence of unavoidable dangling bonds and/or dislocated surface atoms could lead to form imperfect contacts with metals, for example in Cu2O/Au junction devices. Nevertheless, modification of the Cu2O thin film surfaces prior to make contacts with Au has shown the capability to alter the junction properties. Here we report that, the application of surface treatments; annealing and/or sulphidation on specifically the electrodeposited p-Cu2O thin film surfaces, where p-Cu2O thin films were grown in low cupric ion concentrated acetate bath, has influenced the interfacial properties of particular p-Cu2O/Au Schottky junctions compared to the untreated p-Cu2O/Au Schottky junction. This has been well-established by the results of SEM and C-V characterizations of p-Cu2O/Au Schottky junctions. The subsequent annealing and sulphidation of p-Cu2O thin film surfaces have lowered the built-in potential value by 121 mV compared to the untreated Schottky junction. This result reveals the possibility of employing surface treatments on electrodeposited Cu2O thin films in fabrication of high efficient Cu2O based junction devices.Item Smart System Using Lora Technology to Connect Rural Areas Underserved By Existing Internet and Telecommunication Technologies(The Electrochemical Society, 2022) Jayasekaraa, L.D.P.S.; Gurusinghe, T.N.; Wijesooriya, H.E.; Seneviratne, J.A.; Ranaweera, A.L.A.K.; Jayathilaka, K.M.D.C.; Wijesundera, L.B.D.R.P.; Kalingamudali, S.R.D.LoRa, Sigfox, and Narrowband-Internet of Things (NB-IoT) are some of the long-distance, low-power wireless communication technologies developed in the recent past. The proposed system consists of mainly nodes and a gateway as the fundamental system architecture. Nodes only communicate with the gateway individually and the gateway communicates with all the nodes separately and wirelessly. System in this proposed study, uses long range low power RF wireless communication technique for primary data communication, where an Internet connection will not be required for the communication between the gateway and the nodes. Any number of nodes can be paired with the gateway, and the gateway can individually communicate with each and every node. Furthermore, gateways have the ability of storing real-time data. Due to its unique design, the proposed system in this study, can achieve addressable, bidirectional, and continuous data communication even without the Internet connection. The bidirectional communication design of this proposed system facilitates real time and uninterrupted simultaneous handling of monitoring/sensor devices and controller devices without the need of a separate controlling system. As this system consists of those unique features, it is recommended to use in the rural areas underserved by current internet and telecommunication technologies. Furthermore, with the in-built option to get connected to the Internet, this system can be further expanded to an IoT based addressable data communication, processing, and visualization systems by eliminating the major technical problems in typical IoT systems such as interrupted communication and data losses during an Internet connection failure, power concerns and customization issues. This system is highly customizable, and the nodes and the connected devices can be controlled through the gateway or remote dashboard by assigning automated or user defined custom commands. These features together improve the robustness of the system and facilitates enhanced data recovery in case of a failure in the Internet connectivity.Item Effect of pre-surface treatments on p-Cu2O/Au Schottky junctions(Journal of the National Science Foundation of Sri Lanka, 2021) Kafi, F.S.B.; Jayathilaka, K.M.D.C.; Wijesundera, R.P.; Siripala, W.Cuprous oxide (Cu2O) is a suitable semiconducting material in fabrication for low-cost, eco-friendly semiconductor junction devices. Besides the parameterization of the growth conditions of Cu2O, formation of metal contacts impact the overall performance of these type of devices. The existence of unavoidable dangling bonds and/or dislocated surface atoms could lead to form imperfect contacts with metals, for example in Cu2O/Au junction devices. Nevertheless, modification of the Cu2O thin film surfaces prior to make contacts with Au has shown the capability to alter the junction properties. Here we report that, the application of surface treatments; annealing and/or sulphidation on specifically the electrodeposited p-Cu2O thin film surfaces, where p-Cu2O thin films were grown in low cupric ion concentrated acetate bath, has influenced the interfacial properties of particular p-Cu2O/Au Schottky junctions compared to the untreated p-Cu2O/Au Schottky junction. This has been well-established by the results of SEM and C-V characterizations of p-Cu2O/Au Schottky junctions. The subsequent annealing and sulphidation of p-Cu2O thin film surfaces have lowered the built-in potential value by 121 mV compared to the untreated Schottky junction. This result reveals the possibility of employing surface treatments on electrodeposited Cu2O thin films in fabrication of high efficient Cu2O based junction devices.