Institut Penyelidikan dan Teknologi Nano Optoelektronik (INOR) - Tesis
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- 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.
- PublicationPenerapan Gerak Isyarat Mekanisma Pengaratan Besi Dalam Subjek Kimia Dalam Kalangan Murid Tingkatan Empat(2024-04)Hassim, SuziyanaKajian ini bertujuan meneroka penerapan gerak isyarat (GI) mekanisma pengaratan besi dalam kalangan murid Kimia Tingkatan Empat. Dapatan penerokaan GI satu modul GeIsP dibina dan dinilai keperluan modul GeIsP dalam pembelajaran. Pembinaan modul ini menggunakan pendekatan model ADDIE dan telah melalui proses pengesahan. Rekabentuk kajian ini adalah berbentuk pendekatan kualitatif deskriptif. Kajian ini terdapat Dua Fasa. Fasa Satu melibatkan penerokaan GI mengikut pengelasan Mc Neill dalam kalangan 12 orang murid berbeza kelompok. Manakala Fasa Dua mempunyai dua peringkat. Dapatan hasil daripada Fasa Satu , satu modul dibangunkan pada peringkat satu dan peringkat dua melibatkan penilaian persepsi 4 orang guru pakar kimia dan 30 orang guru kimia. Sampel kajian melibatkan sampel bertujuan. Data telah diperoleh melalui senarai semak, pemerhatian, rakaman video, temu bual, dan analisis dokumen. Kesahan kandungan modul dan kebolehpercayaan instrumen juga telah dibuat menggunakan kebolehpercayaan antara penilai/pakar melalui Analisis Indeks Cohen Kappa. Kesahan mencapai purata keseluruhan sebanyak >0.7 Nilai Cohen Kappa. Dapatan kajian menunjukkan terdapat perbezaan dan persamaan penggunaan GI, perbezaan jenis kekerapan GI, perbezaan sela masa pertuturan dan pengekalan kefahaman selepas tiga bulan dalam kelompok murid sederhana dan lemah. Dapatan kajian turut menunjukkan maklum balas positif terhadap pendekatan modul GeIsP yang dibangunkan.
- PublicationGreen Synthesized Ceo2 Nanostructures On Ceo2 And Eu Doped Ceo2 As Passivation Layer For Silicon Based Metal-Oxide-Semiconductor Devices(2024-04)Nsar, Saad Milad AliThis research presented a green synthesis of cerium oxide (CeO2) nanostructures using P. amaryllifolius leaves extract deposited on CeO2 and Europium (Eu3+) doped CeO2 as passivation layer for silicon-based metal-oxide-semiconductor devices. The effects of adding monoethanolamine (MEA) and CeO2 seed layers for the growth of CeO2 nanostructures were investigated. Findings revealed that CeO2 seed layers played an important role in yielding a lower leakage current density (J) (~ 2.5 x 10-6 A cm-2 at gate voltage (Vg) = 2V) when compared with MEA addition due to the improvement of oxygen-rich condition in the CeO2 samples by the seed layers. The effects of post-deposition annealing temperature (600, 700, 800, 900˚C) and ambient (nitrogen-oxygen-nitrogen, forming gas-oxygen-forming, and argon-oxygen-argon) onto structural, morphological, optical, and electrical characteristics of CeO2 and Eu3+-doped CeO2 seed layers were studied. Optimisation of the findings showed that a better J-Vg characteristic was achieved at 800˚C regardless of ambient while the use of nitrogen-oxygen-nitrogen outperformed other ambient because of the passivation of nitrogen to reduce the formation of low dielectric constant (k) silicon dioxide at the CeO2/Si interface. The growth of CeO2 nanostructures on 1 layer of CeO2 seed layer surpassing other samples having 3, 5, and 7 layers has attained good results in terms of a high k value (16.19), a large direct bandgap (3.98 eV), a low J of 5.07 x 10-11 A cm-2 at Vg = 5V as well as large breakdown voltage (12.82 V).
- PublicationModelling Of Inhomogeneous Vertical Underwater Optical Wireless Communication Links(2023-03)Sabril, Muhammad SafiyUnderwater optical wireless communication (UOWC) is becoming increasingly widespread, moving beyond its former restriction to military and defense applications to now also being used in commercial fields. Despite its growing popularity, designing UOWC systems is challenging due to the complex interaction of light with water. To overcome these challenges, this thesis proposes using inhomogeneous medium in UOWC channel modeling, as opposed to the traditional homogeneous medium model which assumes a single constant value for the ocean’s physical and chemical properties. The thesis presents two inhomogeneous models: Model II, based on the variation in chlorophyll concentration, and Model III, which includes the variation in both chlorophyll concentration and refractive index. These models are compared to Model I, the homogeneous model. To estimate the received power, channel bandwidth, and delay spread, the Monte Carlo (MC) technique was improved to account for medium inhomogeneity.
- PublicationEpitaxial Growth Of Iii-V Nitrides Based Light Emitting Diodes By Metal Organic Chemical Vapor Deposition(2023-03)Samsudin, Muhammad Esmed AlifThis research aims to improve the performance of indium gallium nitride (InGaN) based LEDs and to demonstrate a working aluminum gallium nitride (AlGaN) based LEDs through metal organic chemical vapour deposition epitaxy. The effect of gallium nitride (GaN) nucleation growth temperature, superlattice period, and indium composition on InGaN based LED performance was studied. It was found that growing GaN nucleation at 570°C reduced threading dislocations (TDs) in the overgrown GaN layer (which served as the LED base layer). At 570°C nucleation, larger 3D growths (islands) formed, promoting dislocation inclination, and thus reducing TDs. Subsequently, 20 periods of In0.04Ga0.96N/GaN SLs led to reasonable V-pits size. This increased holes injection into the multiquantum well and hence, improved the LED performance. This research also attempted to find out factors which limit the use of GaN substrates in InGaN based LEDs development over sapphire substrates, particularly pattern sapphire substrate (PSS), which is widely used in many studies, including in this research.