Institut Penyelidikan dan Teknologi Nano Optoelektronik (INOR) - Tesis
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- PublicationMultiple Input Multiple Output Visible Light Communication System Sub-Optimization Using Power Allocation Schemes(2025-01)Elewah, Ibrahim Ahmed Mohamed ElsayedLow power consumption and high bit rate are the most important features of visible light communication (vlc) systems. These features are always the main target of any communication system. This study focuses on enhancing data rates and optimizing power consumption in vlc systems. To improve the data rate, multipleinput multiple-output (mimo) has been employed and this technique has an inherited property of combining the data streams and multiplying the data rate. The system was upgraded from a 2×2 to a 4×4 mimo-vlc configuration. To optimize power consumption, two power allocation schemes, gain ratio power allocation (grpa) and normalized gain difference power allocation (ngdpa), were applied to the 4×4 mimo-vlc system. Additionally, a novel modified-ngdpa (m-ngdpa) scheme was proposed, extending the coverage area from 3.14 m² to 4.52 m² and enhancing the sum rate at the coverage boundaries. The mathematical model of the proposed system was presented. The simulation result shows that the 4×4 mimo-vlc system achieves a sum rate of 268 mbps over a 10 mhz bandwidth within a circular coverage area of 1 m radius (3.14 m²). Simulation results indicate that while ngdpa provides a higher sum rate, grpa demonstrates better overall energy efficiency.
- PublicationGrowth Of Gallium Nitride Nanomaterials By Sol-Gel Dip Coating Method(2024-10)Hamid, Maizatul Akmam AbIn the early phase, ethanol-based precursor solution was employed to synthesis gan nanomaterials using diethaolamine as surfactant. First, we investigated the impact of varying withdrawal speeds towards morphological and structural properties of dip coated gan nanomaterials. By optimizing withdrawal speed of 50 mm/min, the xrd spectra shows highest intensity which exhibits lowest micro strain and largest crystallite size among other samples. Further, we investigate the relationship between the impacts of varying dipping cycle towards the crystalline quality of the gan nanomaterials. We observe the emergence of gan(002) plane by raising the total number of dipping process from one to eight cycle. The strength of gan e2 (high) peak reaches its maximum and confirms the phase of wurtzite gan for sample deposited at fifth layer. Next, the effects of varied amount of surfactant towards morphological structure of gan nanomaterials were examined. At 0.75 ml of dea, film consists of hexagonal grains which consist of favoured growth orientations of the gan(002) plane. The xrd analysis confirms the high degree of crystallinity of the sample with the highest value for ga:n atomic ratio. The gan e2 (high) phonon mode from raman fitted gaussian peak reveals that the films deposited at 0.75 ml of dea is relatively stress free. A precursor sol utilizing mono-ethanolamine (mea) and 2-methoxyethanol (2-me) were proposed owing to their superior wettability and rapid rate of evaporation.
- PublicationFabrication And Characterization Of Ingan Based Solar Cell: From Material To Device(2024-01)Yusof, Ahmad SauffiIndium gallium nitride (InGaN) material system has emerged as a promising candidate for high-efficiency solar cells due to its exceptional intrinsic properties. However, developing InGaN-based solar cells faces several challenges, including needing a p-doped layer and producing high-quality indium-rich InGaN alloy. This study explores innovative strategies to overcome these challenges, focusing on the practical development of thick InxGa1-xN-based Schottky solar cells, from material growth to device characterization.
- PublicationIndium Gallium Nitride Based Light Emitting Diode Using Pre-Roughened Backside (N-Face) Gallium Nitride Substrate(2024-01)Alias, Ezzah AzimahThis project attempts to improve the performance of InGaN LEDs grown on GaN substrates. To achieve this goal, three frameworks were proposed. Firstly, by introducing GaN cap layer in multiquantum wells (MQWs). Secondly, by roughening backside (N-face) of GaN substrate using new etching solution and annealing the substrate before roughening. Thirdly, by roughening GaN substrate prior to LED growth.
- PublicationGrowth Of Zno Nanorods Using Hydrothermal And Modified Chemical Bath Deposition For Device Applications(2017-03)M. Mohammad, SabahZinc oxide (zno) is applications in high efficiency electronic and optoelectronic devices. The present study follows two objectives. First, synthesis of vertical and inclined well-aligned zno nanorods (nrs) on a nylon substrate via the hydrothermal method, and subsequently fabricate the highly flexible low-cost ultraviolet photodiodes (uv-pds) and hydrogen (h2) gas sensor devices. Pre-heat treatment of zno seeds/substrate at 180°c with varying duration (0.5-6 h) shows important changes. Morphological observations revealed the formation of aligned hexagonal-like shaped nanorods when the diameter, length (aspect ratio), surface area and density increase with increasing heat treatment time. The x-ray diffraction analysis confirms the formation of wurtzite zno phase with a preferred orientation along (002) direction and enhanced crystallinity. Photoluminescence spectra exhibited a strong and sharp ultraviolet (uv) near band edge emission peak that was higher than that of the broad peak. Temperature and duration to produce uniform zno seeds was 180°c for 3 h.