Institut Penyelidikan dan Teknologi Nano Optoelektronik (INOR) - Tesis
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- PublicationSynthesis And Characterization Of Organic-inorganic Bismuth Halide Perovskites For Photonics Applications(2023-09)Heng, Han YannThe study focused on synthesizing organic-inorganic Bi-halides perovskite compounds using different halides (iodide, bromide, and chloride) in a low-toxic and eco-friendly manner. The aim was to develop Pb-free perovskite materials that are less hazardous for workers in the photonics industry and that can be produced using inexpensive and less complicated processes. In this regards, a hydrophobic phenylammonium cation ([(C6H5)NH3]+) was selected, which is known to contributed to a better sample stability. The synthesis methods involved three different approaches: one step solvent (OSS), OSS added oleic acid (OA), and a non-coordinated solvent method at different temperatures. The stability of the samples were evaluated, and it was observed that the ones synthesized at 60 °C exhibited the best stability for most of the solvents and types of halides. The strong ionic interaction between the BiX63- anion and the short short PhA+ cations in the 0D structure greatly contributed to its stability. In general, the PhA4BiCl6 sample showed the highest stability among the halides due to the stronger attraction between nucleus and electron. The study also involved the growth of a single crystal of PhA4BiI6 using a solvent evaporation technique from which the structure of the zero-dimensional (0D) perovskite compounds was determined, supported by field emission scanning electron microscopy with energy-dispersive X-ray (FESEM-EDX) and Fourier transform infrared (FTIR) spectroscopy results
- PublicationSpin Coated Gallium Oxide Thin Films And The Effect Of Mo-Doping Concentration On Luminescence Properties(2023-07)Wang TiankunBeta-type gallium oxide (β-Ga2O3) with ultra-wide band gap energy and good emission property is suitable for optoelectronic applications such as luminescence devices. However, the growth of good quality β-Ga2O3 films using low cost and simple techniques, particularly the sol-gel spin coating technique, is still remains challenging. For luminescence features, undoped and doped β-Ga2O3 emit multicolour emissions due to the multi-energy level of intrinsic vacancies, which is unsuitable for the display application. From the fundamental and engineering point of view, it is worth investigating the above topics. In this project, the β-Ga2O3 thin films synthesized by the sol-gel spin coating method and their photoluminescence were investigated. For the fabrication, the sol-gel spin coating growth conditions, and processes of the β-Ga2O3 thin films on Si and Al2O3 substrates were investigated. Special treatments on the substrate and the coated layer were conducted to improve the uniformity and smoothness of each coated layer and the final deposited film. Different spin coating cycles, and annealing temperatures were also investigated from the morphologic and optical aspects. Finally, a set of samples with 6-layers spin-coated films and annealed under different temperatures, i.e., from 900 °C, to 1100 °C were prepared. These samples were then subjected to an in-depth X-ray diffraction analysis. The results show that the micro strain is not the key factor for the Bragg peaks broadening. To investigate luminescence properties, a series of Mo-doped β-Ga2O3 on Al2O3 were synthesized. A green luminescence band associated with the Mo ion dxz-dyz band transition appeared slowly with the increase of the Mo-doping concentration.
- PublicationEpitaxial Growth Of Gan On Gan Multi Quantum Well For The Deep Green Light Emitting Diode(2022-10)Abdul Rais, Shamsul AmirThis work has focused on the effort of fabricating the deep green light emitting diode (LED). First, the multi-quantum well (MQW) that was expected to be able to emit a deep green wavelength was designed and fabricated. The MQW was first grown on a patterned sapphire substrate due to nucleation layer and lattice match which are nearest to the gallium nitride (GaN) substrate. The growth of six pairs of GaN/ InxGa1−xN layer that has 12.16/3.35 nm thickness was successfully carried out. The MQW has low crystal defect even when the indium ratio for InxGa1−xN layer growth was 9 times more than gallium. Previous research shows that a high indium ratio in GaN crystal growth would yield high strain but none of these have been observed. The MQW was later inserted into the full LED structure. The LED was grown on the GaN substrate. The resulting LED has good crystal quality, with dislocation of 8.7x107cm-2 . The photoluminescence (PL) spectrum also gives a good result, 568 nm which is in the deep green region. However, the device needed to be annealed to activate the p-type, and the wavelength blue-shifted greatly, 45nm after the annealing process. This prompted the introduction of the indium pre-flow technique to the later growth of the LED samples.
- PublicationGrowth Of Fluorine Doped Zinc Oxide Nanostructures For Ultra-Violet Photodetector Using Modified Chemical Bath-Hydrothermal Method(2022-09)Aminu, MuhammadThe main aim of this research work was the use of modified chemical bath- hydrothermal method for the synthesis of undoped and fluorine doped zinc oxide (FZnO) for ultra-violet (UV) photodetector (PD) application. The effect of fluorine (F) concentration in ZnO properties was investigated on Si substrate, which resulted in enhancement of the crystal quality, optical and electrical properties of ZnO at low F concentration. Subsequently, UV metal-semiconductor-metal (MSM) PD was fabricated based on the undoped ZnO and optimized FZnO. When compared to an undoped ZnO device, the photodetection properties of the optimized FZnO device were enhanced appreciably using the UV-light of 395 nm. The value of photocurrent, responsivity, sensitivity, detectivity, rise time and fall time of the undoped ZnO device were 3.61 μA, 0.22 A/W, 9.7 x103%, 2.2 x1019 Jones, 1.9 s and 1.7 s, respectively. The parameters for the FZnO device on the other hand, were increased to 10.52 μA, 0.66 A/W, 1.1x105%, 1.3x1010 Jones, 90 ms and 110 ms, respectively. Hence, FZnO nanorod (NRs) synthesized using modified hydrothermal method revealed outstanding findings which could be extremely beneficial in the design and manufacture of inexpensive UV MSM PD devices for a variety of optoelectronic applications. In addition,
- PublicationDeposition And Characterisation Of Solution Processed Indium Gallium Zinc Oxide Thin Film On Silicon Substrate(2022-09)Nabihah Binti KasimThis research was conducted with an objective to deposit optimum polycrystalline indium gallium zinc oxide (IGZO) on silicon (Si) substrate by using solution processed method. Specifically, sol-gel method was selected to prepare IGZO precursor solution and spin coating method was used to deposit the film.