Institut Penyelidikan dan Teknologi Nano Optoelektronik (INOR) - Tesis

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Investigation Of Gallium Oxide And Gallium Cerium Oxide Passivation Layers On Silicon And 4h–Silicon Carbide Substrates For Metal-Oxide- Semiconductor Based Devices
(2025-01)
Hedei, Puteri Haslinda Megat Abdul
The evolving technologies in metal-oxide-semiconductor (mos)-based devices have provoked the replacement of conventional silicon (si) by the utilization of wide band gap semiconductor, 4h-silicon carbide (sic). Another encountered issue was related to the limitation of silicon dioxide (sio2) to meet the current demand for smaller, faster and more efficient electronic devices. This has driven the search for alternative materials with higher dielectric constants (k). Therefore, this study focused on investigating gallium oxide (ga2o3) and gallium cerium oxide (gaxceyoz) films sputtered on si and 4h-sic substrates by direct current-radio frequency magnetron co-sputtering for the realization of mos devices. Initial investigation on ga2o3 films was done by varying the post-deposition annealing parameters, such as ambient (nitrogen oxygen-nitrogen (n2-o2-n2), argon, oxygen), dwelling time (30, 60, 90 and 240 min) and temperatures (400, 600, 800 and 1000℃). It was revealed that the ga2o3 film annealed in n2-o2-n2 ambient for 60 min at 800℃ demonstrated the presence of stable β-ga2o3 phase with acceptable structural, optical, morphological and electrical properties due to the incorporation of nitrogen ions into the lattice. The subsequent analysis by employing the optimized annealing parameters to comparative studies amongst ga2o3, cerium doped gallium oxide (cexgayoz) and gaxceyoz on si substrates had emphasized the significance of incorporating gallium ions into the ceo2 lattice.
Multiple Input Multiple Output Visible Light Communication System Sub-Optimization Using Power Allocation Schemes
(2025-01)
Elewah, Ibrahim Ahmed Mohamed Elsayed
Low 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.
Growth Of Gallium Nitride Nanomaterials By Sol-Gel Dip Coating Method
(2024-10)
Hamid, Maizatul Akmam Ab
In 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.
Fabrication And Characterization Of Ingan Based Solar Cell: From Material To Device
(2024-01)
Yusof, Ahmad Sauffi
Indium 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.
Indium Gallium Nitride Based Light Emitting Diode Using Pre-Roughened Backside (N-Face) Gallium Nitride Substrate
(2024-01)
Alias, Ezzah Azimah
This 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.

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