Nurjuliana Juhari
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Preferred name
Nurjuliana Juhari
Official Name
Nurjuliana, Juhari
Alternative Name
Juhari, Nurjuliana Binti
Juhari, Nurjuliana
Juhari, N.
Juhari, N. J.
Main Affiliation
Scopus Author ID
22634152000
Researcher ID
CWQ-4839-2022

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A brief overview of detectors used for terahertz imaging systems

2020-01-08 , Shahrir Rizal Kasjoo , Mohd Mokhar, Mohd Bazli , Nor Farhani Zakaria , Nurjuliana Juhari

This paper presents a short review on terahertz imaging systems based on several types of technology used in the terahertz detection schemes. Some commercial products from ThruVision Systems Limited Company have utilized GaAs Schottky diode detector at 0.25 THz to produce passive terahertz images for public and homeland security. On the other hand, TeraSense Group Incorporated Company has developed and invented a ground-breaking technology which employs sensor consisting of a matrix of plasmonic semiconductor detectors in their latest products to generate terahertz images in the 0.1 - 1.0 THz frequency range. Recently, the utilization of two-terminal unipolar nanodiodes, known as the self-switching diodes (SSDs), as terahertz detectors has shown promising results. The planar structure of SSD not only enables the device to operate at high frequencies due to low intrinsic parasitic capacitance, but also allows the realization of the device using only a single lithography step. This makes the fabrication process of SSDs faster, more simple, and at lower cost when compared to other electronic devices such as Schottky diodes. The development and recent achievement of SSDs as terahertz detectors are also presented in this paper.

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UWB triplet and quadruplet pulses generation employs nonlinear effect in semiconductor optical amplifier nonlinear loop mirror

2020-01-08 , Zahari, Suhaila Mohd , Mohamad Halim Abd. Wahid , Nor Azura Malini Ahmad Hambali , Nurjuliana Juhari , Ghazali N.F. , Shahimin M.M.

Ultrawideband (UWB) triplet and quadruplet pulses generation exploits nonlinear effect in semiconductor optical amplifier (SOA) in nonlinear loop mirror (NOLM) is investigated in this work. Two signals are transmitted through the SOA-NOLM simultaneously to create cross-phase modulation (XPM) effect. Firstly, the XPM causes the production of doublet which later combines for creation of triplet and quadruplet. This technique engages a proper tuning of optical delay and a selection of suitable power in all loops. Besides, injection current of the SOAs also governs the formation of these pulses. Although, frequency of the signals can be varied accordingly, the pulses are limited to certain adjustment that shifted its position in time domain. Furthermore, the set up can also be assessed for monocycle and doublet pulses by extracting the output at several positions. It can be concluded that the design may work as multiple pulses generation. All pulses are examined and compared with their electrical spectrum counterpart for validity of this approach.

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Temperature effects on electrical and structural properties of MEH-PPV/PEIE OLED Device

2020-06-16 , Nurul Afiqah Nor Ismail , Safizan Shaari , Mohd Fairus Ahmad , Norhayati Sabani , Nurjuliana Juhari , Nor Farhani Zakaria

This paper explores the performance of configuration ITO/MEH-PPV/PEIE/Al OLED under the variations of temperature. The MEH-PPV and MEH-PPV/PEIE thin film were deposited on ITO substrates using spin coating technique with fixed spin speed of 3000 rpm and baked at low temperature ranging from 90 °C to 180 °C, respectively. The surface roughness values for MEH-PPV and MEH-PPV/PEIE films were analysed using AFM with 5 μm ' 5 μm scanning area. The roughness of MEH-PPV thin films were reduced from 2.825 nm to 1.625 nm when temperature increased. Contrary to MEH-PPV/PEIE films where the roughness increased linearly up to 3.397 nm when the temperature increased. The maximum absorption peak spectrum obtained from UV-Visible (UV-Vis) was found at 500 nm to 510 nm when baked temperature were varied. Furthermore, the turn on voltage from J-V characteristics gives no specific pattern across different temperature and agreed with the trend of surface roughness values. The turn-on voltage at T = 150 °C gives the lowest value of 3 V. Overall, the variations of low temperature gives an effects on structural and electrical properties of this OLED configuration.

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Analysis of power distribution in mach zehnder interferometer polymer-based waveguide for sensing applications

2022-12 , Mohd. Azarulsani Md. Azidin , Nurjuliana Juhari , Arif Mawardi Ismail , Norhayati Sabani

Two Mach Zehnder Interferometer (MZI) polymer-based waveguide designs namely MZI symmetrical and MZI asymmetrical structures were simulated and analyzed using Optiwave OptiBPM10. The two designs with device size of 4000μm x 300μm exhibit clear optical propagation path when light is simulated through them as well as displaying single mode profile. Highest output power was obtained by the MZI symmetrical design at 0.90 a.u, which suggests better waveguide design for sensing applications.

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Modification of photoanode surface structure via image analysis on organic polymer material based for dye-sensitized solar cell (DSSC) applications

2021-12 , N. Rosli , Norhayati Sabani , MF Ahmad , Mohd. Azarulsani Md. Azidin , Nurjuliana Juhari , NF Zakaria , Mohd Natashah Norizan , Safizan Shaari

In this study, the experiment on the modification of the photoanode with organic polymer material as copolymer template for dye-sensitized solar cell (DSSC) applications has been conducted. The two organic copolymer templates are polystyrene sphere (PS) and poly[2- methoxy-5(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). The modification photoanodes were made using Dr. Blade’s method. These organic copolymer templates were added to improve the surface of the mesoporous titanium dioxide (TiO₂) layer, which is used as the main component in DSSC photoanode. The unmodified TiO₂ photoanode has poor aggregation and porosity of TiO₂. The addition of either MEH-PPV or PS sphere to the photoanode layer was found to affect the surface of mesoporous TiO₂ in terms of porosity, particle size distribution and shape. The analysis of the TiO2 modification was conducted using an image analysis processing method via a 2D scanning electron microscope (SEM) image. The image analysis processing method used was the ImageJ program. The DSSC of modified photoanode is fabricated using metal complex dye, Ruthenium (N719) dye. The data collected from the ImageJ program showed that by adding organic copolymer templates into TiO₂, the porosity of TiO₂ decreased from 45 % to 42 %. From the photovoltaic analysis obtained, the J-V characteristic is recorded with the photoanode of TiO₂ mixed with 1.00 wt% MEH-PPV gave the highest efficiency, which is 0.01 % with the following parameters – Voc = 0.43 V, Jsc = 0.17 mA/cm2 and FF = 0.20. Meanwhile, the photoanode of TiO₂ mixed with 0.50 wt% PS sphere gave the highest efficiency which is 0.08 % with the following parameters – Voc = 0.39 V, Jsc = 0.86 mA/cm2 and FF = 0.25.

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Analysis of an Electrically Induced Optical Waveguide in a c-axis Barium Titanate Thin Film

2021-12-01 , Arif Mawardi Ismail , Prabakaran A/L Poopalan , Nurjuliana Juhari , Mohd. Azarulsani Md. Azidin

In this paper, we report our analysis of an electrically generated optical waveguide in a c-axis barium titanate (BTO) thin film. The waveguide consists of a BTO thin film which is sandwiched between two electrodes. The thin film forms a waveguide when a voltage difference is applied across the electrodes. It is found that the formed waveguide supports both TE and TM modes, with TM modes more tightly confined within the waveguide than TE modes. The possibility to turn the waveguide on and off simply by turning the electric field on and off may prove useful for optical switching.

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The Effect of Different Solvents in Natural Dyes from Roselle (Hibiscus Sabdariffa) and Green Tea Leaves (Camellia Sinensis) for Dye-Sensitized Solar Cell

2021-03-01 , Norhisamudin N.A. , Norhayati Sabani , Shamimin M.M. , Nurjuliana Juhari , Shaari S. , Ahmad M.F. , Zakaria N.

A dye-sensitized solar cell (DSSC) fabricated using anthocyanin or chlorophyll natural dye extract coming from Roselle (Hibiscus Sabdariffa) and Green Tea leaves (Camellia Sinensis). Both dye pigmentations were extracted using different alcohol-based solvent, namely, ethanol, methanol and mixed (ethanol + methanol) to identify whether the different solvents give the effect during the dye extraction. The performance of the electron transfer interaction between the natural dye and Titanium Dioxide (TiO2) was determined. The photovoltaic response of DSSC was collected by recording the data of I-V characteristic under illumination. The DSSC using the Roselle dye extract yielded the following results; Voc = 0.001 V, Jsc = 0.00868(mA/cm2), FF = 0.3554 and η = 0.00142% which is coming from the mixed solvent. On the other hand, the green tea dye extract yielded the following results; Voc = 0.3985, Jsc = 0.000797 (mA/cm2), FF = 0.3985 and η = 0.0000752% which is coming from the methanol solvent.

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Optimization of MEH-PPV based single and double-layer TOLED structure by numerical simulation

2021-12 , T. Kersenan , Nor Farhani Zakaria , Safizan Shaari , Norhayati Sabani , Nurjuliana Juhari , Meor Ahmad Faris bin Meor Ahmad Tajudin , A.F.A Rahim

In this work, we simulated and characterized Poly [2-methoxy-5-(2’-ethylhexyloxy)-1, 4-phenylene vinylene] (MEH-PPV) based single and double-layer TOLED by using Silvaco ATLAS device simulator to achieve prominent values of electrical and optical properties of the device. MEH-PPV were used as the emitting layer (EML) in the single-layer, while addition of Poly [(3,4-ethylene dioxythiophene)-poly(styrene sulfonate)] (PEDOT-PSS) as the electron transport layer (ETL) were conducted in double-layer TOLED simulation. The EML and ETL thickness in both structures were varied between 10 – 150 nm, respectively, to observe and understand the underlying physics of the relation in the layer thickness to the electrical and optical characteristics. Furthermore, variation of the EML/ETL thickness ratio from 1:1 to 5:1 (with thickness in between 10 to 50 nm) had also been conducted. From this work, it is understood that the thickness of the EML layer plays the most important role in TOLED, and by balancing the carrier injections and recombination rate in appropriate EML/ETL thickness ratio, the electrical and optical properties can be improved. By optimizing the EML/ETL thickness and thickness ratio, an optimal forward current of 1.41 mA and luminescent power of 1.93e-18 W/μm has been achieved with both MEH-PPV and PEDOT-PSS layer thickness of 10 nm (1:1 ratio), respectively. The results from this work will assist the improvement of TOLED device to be implemented widely in low power and transparent electronic appliances.

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Characterization of all-optical Tofolli and Peres gates employing optimized SOA-NOLM

2020-01-08 , Nur Hafizah Ghazali , Mohamad Halim Abd. Wahid , Nor Azura Malini Ahmad Hambali , Nurjuliana Juhari , Zahari S.M. , Shahimin M.M.

In this work, all-optical reversible gates namely Tofolli and Peres are studied and characterized. The gates utilize semiconductor optical amplifier (SOA) in nonlinear loop optical mirror (NOLM). The reversible gates are performed at data rate 10 Gb/s with narrow Gaussian pulses as input signals. Delay of 130 ps and injection current of 170 mA have displayed the optimum outputs in the SOA-NOLM. Extinction ratio is greatly reduced, thus less noise interferes the logic operation in this simple technique. It is observed that Peres gate has shown a higher output power compare to Toffoli gate. This could be due to multiple amplification that are experienced by the signals. Other than the gain, injection current and delay are shown to give major effect in producing the correct bits at the outputs. The SOA-NOLM also can be cascaded for other arithmetic signal processing operation at high frequency. It is also recorded that the design consumes low power especially in small signal gain process. Thus, the design indicates its versatility to be executed in photonic integrated circuits for ultrafast signal control through fiber networks.

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Optimization of gold nanoparticles electrodeposition duration on screen printed electrode to enhance electrochemiluminescence of nitrogen-doped carbon dots

2023-12 , Nurul Izzati Akmal Mohd Azman , Nur Syakimah Ismail , Nur Hamidah Abdul Halim , Nurjuliana Juhari , Norhayati Sabani , Toibah Abd Rahim , Siti Aisyah Shamsudin , Eiichi Tamiya

In this work, the electrodeposition method was utilized to form gold nanoparticles on a carbon screen-printed electrode (SPE) using chronoamperometry at -0.4 V with various durations from 50 to 200 seconds. Scanning Electron Microscopy (SEM) images have proven that the electrodeposition method is capable of uniformly forming AuNPs on SPE (AuNPs- SPE). Apart from that, electrodeposition durations have increased the size of AuNPs by up to 66% based on average size measurements using ImageJ software. It can be observed that long electrodeposition durations permit the agglomeration of AuNPs on the electrode surface. The effect of electrodeposition duration on electrocatalytic performance in potassium ferricyanide and electrochemiluminescence (ECL) intensity of nitrogen-doped carbon dots (NCDs) was evaluated. Cyclic voltammetry (CV) of ferricyanide demonstrates that as the electrodeposition duration increases, AuNPs-SPE shows better electrochemical performance than bare SPE. ECL of NCDs displays that 100 s electrodeposition durations give the highest ECL intensity of 184% compared to bare SPE and have been chosen as the optimum parameter. The ECL mechanisms of bare SPE and AuNPs-SPE reveal that AuNPs- SPE has greater electrochemical and ECL performance than bare SPE, as evidenced by the CV of AuNPs-SPE having a faster reduction current, which rises to 87.2% ECL intensity and 510 mV faster ECL occurrence. These phenomena confirmed that the electrodeposition of AuNPs has improved the conductivity of SPE.

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