Ayu Wazira Azhari
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Preferred name
Ayu Wazira Azhari
Official Name
Ayu Wazira, Azhari
Alternative Name
Ayu, A. W.
Azhari, Ayu W.
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Scopus Author ID
24450001400
Researcher ID
ABA-7808-2020

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Annealing effects on Polycrystalline Silicon Germanium (SiGe) thin films grown on nanostructured silicon substrates using thermal evaporation technique

2022-10 , Ayu Wazira Azhari , Eop, T. S. , Dewi Suriyani Che Halin , Uda Hashim , Sopian, K. , Zaidi, S. H.

Polycrystalline SiGe thin films have been formed after thermal annealing of formerly vacuum evaporated a-Ge layers. The a-Ge thin films were deposited onto nanostructured Si substrates via low-cost thermal evaporation method. Then, the films were annealed in a furnace at temperatures ranging from 400 °C to 1000 °C resulting in crystal growth of the SiGe layers. In general, the annealing temperature for polycrystalline SiGe is between 600 °C – 800 °C. The crystalline structure of the SiGe layer is improved as a function of increased temperature. This is shown by the low FWHM of about 5.27 as compared to the commercially available Ge substrates where the FWHM value is about 5.06. This method also produces more relax Ge layer where the strain value is 0.261.

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Microstructure evolution of Ag/TiO₂ thin film

2021 , Dewi Suriyani Che Halin , Kamrosni Abdul Razak , Mohd Arif Anuar Mohd Salleh , Mohd Izrul Izwan Ramli , Mohd. Mustafa Al Bakri Abdullah , Ayu Wazira Azhari , Kazuhiro Nogita , Hideyuki Yasuda , Marcin Nabiałek , Jerzy J. Wysłocki

Ag/TiO₂ thin films were prepared using the sol-gel spin coating method. The microstructural growth behaviors of the prepared Ag/TiO₂ thin films were elucidated using real-time synchrotron radiation imaging, its structure was determined using grazing incidence X-ray diffraction (GIXRD), its morphology was imaged using the field emission scanning electron microscopy (FESEM), and its surface topography was examined using the atomic force microscope (AFM) in contact mode. The cubical shape was detected and identified as Ag, while the anatase, TiO₂ thin film resembled a porous ring-like structure. It was found that each ring that coalesced and formed channels occurred at a low annealing temperature of 280 °C. The energy dispersive X-ray (EDX) result revealed a small amount of Ag presence in the Ag/TiO₂ thin films. From the in-situ synchrotron radiation imaging, it was observed that as the annealing time increased, the growth of Ag/TiO₂ also increased in terms of area and the number of junctions. The growth rate of Ag/TiO₂ at 600 s was 47.26 µm2/s, and after 1200 s it decreased to 11.50 µm2/s and 11.55 µm2/s at 1800 s. Prolonged annealing will further decrease the growth rate to 5.94 µm2/s, 4.12 µm2/s and 4.86 µm2/s at 2400 s, 3000 s and 3600 s, respectively.

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A Study on the Environmental Impact During Distribution and Disposal Stages for the 3-Ply Face Masks by Using Life Cycle Assessment (LCA)

2022-01-01 , Chow Suet Mun Christine , Tengku Nuraiti Tengku Izhar , Irnis Azura Zakaria , Sara Yasina Yusuf , Ayu Wazira Azhari , Boboc M.

The demand of face masks had increased tremendously due to pandemic outbreak of COVID-19, leading to the increment production rate of face masks in Malaysia. Waste is also produced at the same time, resulting impacts towards the environment. Due to the land scarcity issue in Malaysia, the end of life treatment for the waste is taken into consideration. The study tools used in this study is life cycle assessment (LCA) to identify the significant potential environmental impact produced during the life cycle stages for distribution and disposal through GaBi Education Software. The disposal stage between landfill and incineration of the 3-Ply face masks is studied to determine the end of life treatment for it. The impact assessment method selected in this study is CML 2001-Jan 2016 with the environmental indicator of Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP) and Ozone Depletion Potential (ODP). GWP results in producing highest impact to the environment during both distribution and disposal stages. The impact of GWP also relates to the climate change. Modern incineration is recommended to overcome the issue of land scarcity in Malaysia as the amount of waste by 3-Ply face masks are increasing due to the pandemic COVID-19, reducing the impacts towards the environment.

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Metal induced crystallization of polycrystalline silicon germanium: The morphological study between nickel and copper

2023 , T. S. Eop , Ayu Wazira Azhari , L. Mohamad Jazi , K. S. Ting , Dewi Suriyani Che Halin , Abdul Kareem Thottoli

In this study, metal induced crystallization technique is used in to obtain the lower temperature point in crystallization. Two different metals with one non-metal configuration as a baseline i.e. SiGe/Ni, SiGe/Cu and SiGe. A simple metal-assisted chemical etching method is used to fabricate the Si nanopillar, with Ag acting as a catalyst. Following by deposition of metal namely nickel (Ni) and copper (Cu) then undergo thermal annealing from 200 ℃ until 1000 ℃ to improve the crystallinity of the Ge layer. Morphological studies of surface area were conducted using scanning electron microscopy (SEM). The results show that the crystallization temperature of SiGe with Ni was obtained at 400 ℃ while the crystallization temperature of SiGe without any metal was obtained at 600 ℃. Meanwhile the crystallinity, for SiGe/Cu only occurs in very low level where the structure did not change until the annealing was conducted at 600 ℃. Based from these result, it is proved that the metal can help lowering the crystallization temperature and improving the defects of SiGe.

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Effect of temperature and amount of Ag on TiO₂ thin film synthesised via sol–gel method

2025-02 , Dewi Suriyani Che Halin , Kamrosni Abdul Razak , Dharshini Karikalan , Lukasz Kaczmarek , Sebastian Miszczak , Ayu Wazira Azhari , Mohd Arif Anuar Mohd Salleh , Nur Izzati Muhammad Nadzri , Juyana A. Wahab , Mohd. Mustafa Al Bakri Abdullah

TiO₂ sol was produced via the sol–gel method with different amounts of AgNO₃ as the source of Ag. The Ag/TiO₂ thin film was obtained by spin coating and was annealed at various annealing temperatures (300°C, 400°C and 500°C) for 1 h. The effect of different amounts of AgNO₃ and different annealing temperatures on the TiO₂ thin films was studied by characterising the phase composition, surface morphology and water contact angle. Results from the x-ray diffraction (XRD) pattern show that with the addition of AgNO₃, Ag/TiO₂ can be formed at low annealing temperatures (300°C). At increased annealing temperatures (400°C and 500°C) and amounts of AgNO₃ (1.0 ml and 1.5 ml), Ag₂O and Ag₃O4 phases were observed. Flakes or flaky islands were formed on the thin film due to thermal expansion mismatch between the film and substrate, residual stress within the film or the release of volatile species when annealed at a low temperature of ⁓300°C. Increasing the temperature to 500°C resulted in the growth and coalescence of the flaky islands by the surface diffusion of adsorbed atoms (adatoms) and their annexation to the surface of existing nuclei. The water contact angle provides valuable insight into the surface interactions between water droplets and the surface of Ag/TiO₂ thin films. It was found that at 1.5 ml AgNO₃, the increased annealing temperature from 300°C to 500°C decreased the water contact angle of Ag/TiO₂ thin films from 83.86° to 34.62°, forming superhydrophilic properties, which indicated its excellent potential as a photocatalyst.

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Effect of polyethylene glycol and sodium dodecyl sulphate on microstructure and self-cleaning properties of graphene oxide/TiO2 thin film

2020-09-01 , Azani A. , Dewi Suriyani Che Halin , Kamrosni Abdul Razak , Mohd. Mustafa Al Bakri Abdullah , Norsuria Mahmed , Muhammad Mahyiddin Ramli , Mohd Arif Anuar Mohd Salleh , Mohd Fairul Sharin Abdul Razak , Ayu Wazira Azhari , Chobpattana V. , Kaczmarek L.

In this study, a sol gel procedure for preparation of TiO2 thin films with graphene oxide (GO) was developed. The effect of PEG and SDS addition on the microstructure of the films as well as the photocatalytic activity of the thin film was also investigated. The morphology and surface structure of the films were studied by SEM and AFM while the photocatalytic activity of the films was analyzed by measuring the degradation of methylene blue under sunlight irradiation using UV-Vis spectrophotometer. It was found that GO/TiO2 thin film with PEG shows a smaller and porous particle while GO/TiO2 thin film with SDS formed a very smooth surface and very fine particles. Therefore, in AFM analysis reveals that surface roughness decreases with the addition of PEG and SDS. Finally, the photocatalytic activity showed that GO/TiO2 thin film with SDS have the most effective self-cleaning property which degrade 64% of methylene blue that act as model of contaminants.

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Annealing Effects on Polycrystalline Silicon Germanium (SiGe) Thin Films grown on Nanostructured Silicon Substrates using Thermal Evaporation Technique

2022-10-01 , Ayu Wazira Azhari , Eop T.S. , Dewi Suriyani Che Halin , Sopian K. , Uda Hashim , Zaidi S.H.

Polycrystalline SiGe thin films have been formed after thermal annealing of formerly vacuum evaporated a-Ge layers. The a-Ge thin films were deposited onto nanostructured Si substrates via low-cost thermal evaporation method. Then, the films were annealed in a furnace at temperatures ranging from 400 °C to 1000 °C resulting in crystal growth of the SiGe layers. In general, the annealing temperature for polycrystalline SiGe is between 600 °C – 800 °C. The crystalline structure of the SiGe layer is improved as a function of increased temperature. This is shown by the low FWHM of about 5.27 as compared to the commercially available Ge substrates where the FWHM value is about 5.06. This method also produces more relax Ge layer where the strain value is 0.261.

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Microplastics in facial cleanser: extraction, identification, potential toxicity, and continuous-flow removal using agricultural waste–based biochar

2023-05-01 , Hanif M.A. , Naimah Ibrahim , Farrah Aini Dahalan , Umi Fazara Md Ali , Masitah Hasan , Ayu Wazira Azhari , Jalil A.A.

Microplastic (MP) is an emerging contaminant of concern due to its ubiquitous quantity in the environment, small size, and potential toxicity due to strong affinity towards other contaminants. In this work, MP particles (5–300 μm) were extracted from a commercial facial cleanser and determined to be irregular polyethylene (PE) microbeads based on characterization with field emission scanning electron microscopy (FESEM) and Raman spectroscopy. The potential of extracted MP acting as toxic pollutants’ vector was analyzed via adsorption of methylene blue and methyl orange dye where significant dye uptake was observed. Synthetic wastewater containing the extracted MP was subjected to a continuous-flow column study using palm kernel shell and coconut shell biochar as the filter/adsorbent media. The prepared biochar was characterized via proximate and ultimate analysis, FESEM, contact angle measurement, atomic force microscopy (AFM), and Fourier transform infrared (FTIR) spectroscopy to investigate the role of the biochar properties in MP removal. MP removal performance was determined by measuring the turbidity and weighing the dry mass of particles remaining in the effluent following treatment. Promising results were obtained from the study with highest removal of MP (96.65%) attained through palm kernel shell biochar with particle size of 0.6–1.18 mm and continuous-flow column size of 20 mm. Graphical abstract: [Figure not available: see fulltext.].

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Fabrication and simulation of silicon nanogaps pH sensor as preliminary study for Retinol Binding Protein 4 (RBP4) detection

2025-01 , M. I. Hashim , Mohammad Nuzaihan Md Nor , Mohamad Faris Mohamad Fathil , M. Shaifullah A.S , C. Y. Chean , Nur Hamidah Abdul Halim , Zarimawaty Zailan , Mohd Khairuddin Md Arshad , Muzamir Isa , Ayu Wazira Azhari , M. Syamsul , Rozaimah A.T.

In this research, a silicon nanogap biosensor has the potential to play a significant role in the field of biosensors for detecting Retinol Binding Protein 4 (RBP4) molecules due to its unique nanostructure morphology, biocompatibility features, and electrical capabilities. Additionally, as preliminary research for RBP4, a silicon nanogap biosensor with unique molecular gate control for pH measurement was developed. Firstly, using conventional lithography followed by the Reactive-ion etching (RIE) technique, a nanofabrication approach was utilized to produce silicon nanogaps from silicon-on-insulator (SOI) wafers. The critical aspects contributing to the process and size reduction procedures were highlighted to achieve nanometer-scale size. The resulting silicon nanogaps, ranging from 100 nm to 200 nm, were fabricated precisely on the device. Secondly, pH level detection was performed using several types of standard aqueous pH buffer solutions (pH 6, pH 7, pH 12) to test the electrical response of the device. The sensitivity of the silicon nanogap pH sensor was 7.66 pS/pH (R² = 0.97), indicating that the device has a wide range of pH detecting capacity. This also includes the silicon nanogap biosensor validated by simulation, with the sensitivity obtained being 3.24 μA/e.cm² (R² = 0.98). The simulation of the sensitivity is based on the interface charge (Qf) that represents the concentration of RBP4. The results reveal that the silicon nanogap biosensor has excellent characteristics for detecting pH levels and RBP4 with outstanding sensitivity performance. In conclusion, this silicon nanogap biosensor can be used as a new electrical RBP4 biosensor for biomedical diagnostic applications in the future.

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Numerical simulation of lead-free tin and germanium based all perovskite tandem solar cell

2023-12 , Rae-Ann Lim Jia En , Ayu Wazira Azhari , Dewi Suriyani Che Halin , Suhaila Sepeai , Norasikin Ahmad Ludin

The ability to customize the materials bandgaps makes perovskite solar cells a promising candidate for hybrid-tandem applications. This allows them to effectively utilize parts of the solar spectrum that silicon-based solar cells cannot efficiently capture, resulting in higher absorption coefficients. However, there is a lack of research on lead-free all-perovskite tandem solar cells, and secondary data on materials is limited. One of the main challenges in previous studies is the high cost and solid structure of traditional silicon-based solar cells, which require significant storage space. Additionally, lead-based perovskite solar cells pose environmental concerns due to their water solubility and potential harmful effects upon consumption. To address these issues, thin-film perovskite solar cells with liquid solvents are employed in the solar cell design. Lead is replaced with germanium and tin-based perovskites, which exhibit comparable photovoltaic performance to silicon. In the present work, the OghmaNano simulation tool was utilized to conduct numerical simulation of the perovskite design. The perovskite solar cell layers were structured as follows: FTO/ZnO/MAGeI3/Spiro-OMeTAD/FAMASnGeI3/Cu2O/Au. The variables considered included optimum layer thicknesses and bandgaps, as well as the most suitable materials for the ETL and HTL, aiming to obtain the highest efficiency. Based on the simulation results, the proposed perovskite structure shows remarkable photovoltaic parameters. The Voc was measured at 0.84 V Jsc of 16.1 mA/cm2, FF of 0.825, and PCE that reached 11.12%. This project contributes to future research on materials for the ETL and HTL of lead-free, tin and germanium based APTSCs.

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