Institut Penyelidikan dan Teknologi Nano Optoelektronik (INOR) - Tesis

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Development Of Polymer/Al-Ag-Zno Nanocomposites For Uv-Shielding Applications
(2025-04)
Khalaf, Hameed Naser Khalaf
This thesis presented the development of polymer/ aluminum (al)-silver (ag)-zinc oxide (zno) nanocomposites (ncs) with single-metal (al, ag, or zno) or bimetallic (al+ag), (al+zno), and (ag+zno) configurations for ultraviolet (uv)-shielding applications. The casting technique was employed for the fabrication of flexible foil-shaped (al-ag-zno), (al+ag), (al+zno), and (ag+zno) nanoparticles (nps). The (al-ag-zno) nps added as filler at 0, 1, 5, 10, and 15 wt%, while (al+ag), (al+zno), and (ag+zno) with 5 wt% to polymer matrices such as polyvinyl alcohol (pva), polymethyl methacrylate (pmma), and polystyrene (ps). The morphology of al, ag, and zno nps, with a size range of 20 to 160 nm, was analyzed using the transmission electron microscopy (tem) technique. Energy dispersive x-ray (edx) examination showed the presence of al, ag, and zno nps in the samples at different concentrations, confirming their dispersion inside the polymer matrix. Uv-visible transmittance spectra showed low transmittance in the uv range, with a contrasting trend observed relative to nps concentrations. Uv-visible absorption spectra showed high absorption in the uv region, which was inversely related to the presence of (al+ag), (al+zno), and (ag+zno) ncs.
Synthesis And Characterization Of Plasmonic-Assisted Photodetection Performance Based On Porous Silicon
(2025-02)
Abed, Shireen Mohammed
This thesis investigates the synthesis and characterization of metal-semiconductor-metal (msm) and p-n heterojunction organic-inorganic hybrid photodetectors based on the noble metal nanoparticles (nps) plasmonic-assisted and utilizing porous silicon (psi) substrates using a simple and low-cost method to enhance photodetection performance across the ultraviolet-visible-near infrared (uv-vis-nir) spectrum. First, psi were fabricated on bare silicon using photoelectrochemical etching. The resulting psi substrate demonstrated high porosity, with pore diameters ranging from 199 to 750 nm, an average pore length of 3.6 μm, and a root mean square (rms) roughness value of 70 nm. Field electron scanning electron microscopy (fesem) images revealed that zinc oxide (zno) seeds deposited using the low-cost vibration-assisted drop-casting method (vadcm) on psi effectively infiltrated the pores and adhered to the inner walls, which led to the growth of the zno nanorods (nrs) by modified hydrothermal method inside the pores in different directions and a more significant number of contact point connections between rods, whereas those deposited by radio frequency (rf) sputtering accumulated on the surface, which led to the hydrothermal growth of the zno nrs as a layer on the psi substrate.
Improvement Of Structural Design Of Algan/Gan Based Hemt For High Performance Power Devices
(2025-02)
Mihat, Muhaimin Haziq
This research focuses on the introduction of innovative structural designs aimed at addressing the multifaceted challenges associated with algan/gan hemts. Simulations are first validated against experimental data to ensure reliability. The investigated structures are then categorized into two; below and above the gate region. To address the high electric field concentrations near the metal contact edges, this thesis proposes new structural variations below the gate, which includes triple-trench, dual-notch, and an algan-graded channel with varied al composition along the channel. These approaches optimize the electric field distribution and reduce the likelihood of current collapse through enhanced mobility. Another focus is gate reliability, particularly gate leakage and on-state resistance through designs above the gate, such as a gate airgap, created by physically separating the metal contact from the semiconductor. Further optimizations include p-gan layer thickness, p-gan doping concentration, and device dimensions, balancing performance and reliability. This includes a comprehensive analysis of the trade-offs in gate length, gate-drain spacing, and surface passivation materials to reduce gate leakage, and a recessed p-gan gate is also developed for safer on-state operation. Overall, a 478% improvement in breakdown properties and a 403% increase in maximum drain current have been realized with the graded channel.
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.

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