Nor Farhani Zakaria
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Nor Farhani Zakaria
Official Name
Nor Farhani, Zakaria
Alternative Name
Zakaria, N. Fa
Zakaria, N. F.
Zakaria, N.
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Scopus Author ID
57191032557
Researcher ID
AFT-7132-2022

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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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Improved rectification performance and terahertz detection in hybrid structure of self-switching device (SSD) and planar barrier diode (PBD) using two-dimensional device simulation

2020-01-01 , Nor Farhani Zakaria , Shahrir Rizal Kasjoo , Muammar Mohamad Isa , Zarimawaty Zailan , Mohd Khairuddin Md Arshad , Song A.

Recently, simulations of In0.48Ga0.52As-based Planar Barrier Diode (PBD) and Self- Switching Device (SSD) as millimeter-wave rectifiers were reported. Both PBD and SSD have a planar structure, but with different insulating shapes and working principles. In this work, a hybrid structure of the reported PBD and SSD in a parallel configuration is proposed, to exploit the advantages of each device. The advantages of high rectifying properties in the SSD and fast switching rate of the PBD are combined in this hybrid structure in order to obtain an improved rectification performance at zero-bias in the near terahertz frequency region. Analysis of the curvature co-efficient, γ, which is defined as the ratio of the second order to the first order derivative of the device’s I-V function was performed to evaluate the rectification performance. AC transient analyses were then executed in various frequencies to imitate the high-frequency signal inputs. By using this hybrid structure, the highest value of γ achieved has been improved to ~19 V-1 at 70 mV, and ~6 V-1 at zero- bias (compared to the previous results on PBDs). The estimated cut-off frequency obtained was ~360 GHz (0.36 THz), operating at zero-bias.

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A study on electrical performance of SiC-based self-switching diode (SSD) as a high voltage high power device

2023-12 , N. Z. A. A. Sha’ari , Nor Farhani Zakaria , Shahrir Rizal Kasjoo , Mohd Natashah Norizan , Ili Salwani Mohamad , Mohd Fairus Ahmad , Shamsul Amir Abdul Rais , Banu Poobalan , Norhayati Sabani , A. F. A. Rahim

The Self-switching Diodes (SSDs) have been primarily researched and used in low-power device applications for RF detection and harvesting applications. In this paper, we explore the potential of SSDs in high-voltage applications with the usage of Silicon Carbide (SiC) as substrate materials which offers improved efficiency and reduced energy consumption. Optimization in terms of the variation in the interface charges, metal work function, and doping concentration values has been performed by means of a 2D TCAD device simulator. The results showed that the SSD can block up to 600 V of voltage with an optimum interface charge value of 1013 cm-2, making them suitable for higher voltage applications. Furthermore, it also found that the work function of the metal contact affected the forward voltage value, impacting the current flow in the device. Variation in doping concentrations also resulted in higher breakdown voltages and significantly increased forward current, leading to an increased power rating of 27 kW. In conclusion, the usage of 4H-SiC-based SSDs shows a usable potential for high-voltage applications with optimized parameters. The results from this research can facilitate the implementation of SSD in the development of high-power semiconductor devices for various industrial applications.

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Photoluminescence measurement of triplet sensitizer-emitter solution using a customized 3D-printed sample holder

2024-06 , Kelvin Voon Yan Jie , Safizan Shaari , Mohd Fairus Ahmad , Nor Farhani Zakaria , Norhayati Sabani

This study explores the photoluminescence (PL) measurement of triplet sensitizer-emitter (TSE) solutions using a custom 3D-printed sample holder, within the context of triplet-triplet annihilation based molecular photon upconversion (TTA-UC) systems targeting the Vis-to-UV spectral region. TTA-UC converts low-energy visible photons to higher-energy ultraviolet (UV) photons, holding promise for solar energy harvesting and photonics applications. Two TSE couples, 4CzIPN/TP and 4CzIPN/QP, were investigated, and their upconverted fluorescence spectra showed peaks at 344 nm and 354 nm / 370 nm, respectively, confirming efficient upconversion capabilities. The 3D-printed sample holder facilitated reproducible PL measurements, enabling the calculation of quantum yields (ΦUC). The 4CzIPN/TP and 4CzIPN/QP couples exhibited low quantum yields (0.028% and 0.043%, respectively), suggesting the need for improved deoxygenation methods to enhance the triplet-triplet annihilation process and overall quantum efficiency. Despite modest yields, successful UV upconverted fluorescence observation underscores the feasibility of the Vis-to-UV TTA-UC system. This study provides insights into TTA-UC optimization and demonstrates the utility of the 3D-printed sample holder for affordable and precise PL measurements, paving the way for future advancements in photonics and solar energy applications.

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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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Silicon Self-Switching Diode (SSD) as a Full-Wave Bridge Rectifier in 5G networks frequencies

2022 , Tan Yi Liang , Nor Farhani Zakaria , Shahrir Rizal Kasjoo , Safizan Shaari , Muammar Mohamad Isa , Arun Kumar Singh , Mohd Khairuddin Md Arshad

The rapid growth of wireless technology has improved the network’s technology from 4G to 5G, with sub-6 GHz being the centre of attention as the primary communication spectrum band. To effectively benefit this exclusive network, the improvement in the mm-wave detection of this range is crucial. In this work, a silicon self-switching device (SSD) based full-wave bridge rectifier was proposed as a candidate for a usable RF-DC converter in this frequency range. SSD has a similar operation to a conventional pn junction diode, but with advantages in fabrication simplicity where it does not require doping and junctions. The optimized structure of the SSD was cascaded and arranged to create a functional full-wave bridge rectifier with a quadratic relationship between the input voltage and outputs current. AC transient analysis and theoretical calculation performed on the full-wave rectifier shows an estimated cut-off frequency at ~12 GHz, with calculated responsivity and noise equivalent power of 1956.72 V/W and 2.3753 pW/Hz1/2, respectively. These results show the capability of silicon SSD to function as a full-wave bridge rectifier and is a potential candidate for RF-DC conversion in the targeted 5G frequency band and can be exploited for future energy harvesting application.

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The structural and electrical characterization of PEDOT:PSS/MEH-PPV doped with PEIE OLED fabricated using spin coating technique

2020-01-08 , Juhari N. , Shukri N.I.A. , Norhayati Sabani , Safizan Shaari , Mohd Fairus Ahmad , Nor Farhani Zakaria

This paper investigates the performance of the uniformity and absorption spectrum of MEHPPV+PEIE thin films also the electrical properties for configuration of ITO/PEDOT: PSS/MEH+PEIE/Al. The sample used 0.5 wt % of PEDOT: PSS solution while 5 mgml-1 concentration of MEH-PPV solution was doped with four different concentrations of PEIE with values of 0.1 wt%, 0.3 wt%, 0.5 wt% and 0.7 wt% respectively. The untreated PEDOT: PSS and MEH-PPV+PEIE was deposited using spin coating technique at a fixed spun speed of 3000 rpm to obtain smooth surface roughness thin film. The root mean square (RMS) value, absorption spectrum and current density (A/cm-2) of the PEDOT: PSS and MEH-PPV+PEIE films were analyzed using Atomic Force Microscope (AFM), UV-Visible (UV-Vis) Spectrophotometer and Semiconductor Parametric Analyzer (SPA), respectively. The surface roughness of the films were linearly increased when the dopant concentration increased with the maximum RMS value of ∼4.74 nm. Besides, absorption peak wavelength also was red-shifted from 500 nm to 551 nm under an influence of PEIE dopant concentrations. However, the turn on voltage gives no significant trend when dopant concentration was increased but the emission of the light was emitted when the voltage was below 8 V. Among four different dopant concentrations of MEH-PPV+PEIE, the brighter light emission was observed at 0.3 wt% of PEIE. Apparently, the concentration of dopant solution gives a significant contribution to the performance of OLED in terms of structural, optical and electrical properties.

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The modelling of SiC Gate Oxide thickness based on thermal oxidation temperatures and durations for high-voltage applications

2023 , Nuralia Syahida Hashim , Banu Poobalan , Nor Farhani Zakaria , Manikandan Natarajan , Safizan Shaari

This research has shown that the oxide thickness for silicon carbide (SiC) based wide materials can be predicted using regression techniques in wet/dry nitrided or wet/dry non-nitrided thermal oxidation process conditions for high voltage applications by employing 2 different regression techniques: Polynomial and linear regression. The R-squared (R2) and Mean Absolute Percentage Error (MAPE) techniques are used to evaluate the regression models. Furthermore, this work investigates and presents a calculation of gate oxide thickness that is correlated to gate voltage ranges for high voltage applications. In this work, the thermal oxidation process environment is classified into 3 different processing conditions: conventional (dry and wet), dry nitrided (NO,N2O), and wet nitrided (HNO3 vapour). The findings from this study showed that wet oxidation combined with nitrided elements can produce thicker and better-quality gate oxide as compared to conventional dry and wet oxidation techniques. The outcome of this work clearly shows that gate oxide thickness may be derived from silicon carbide-based wide-bandgap materials utilizing linear and polynomial approaches using thermal oxidation durations at different temperatures for high-power applications. The regression models and formulations produced in this work are expected to aid the researchers in determining appropriate oxide thickness under practicable process conditions, with the exception of real thermal oxidation process conditions. Hence, the outcome of this work is expected to save the processing time, material, and cost of the power semiconductor device fabrication technology, mainly for high voltage applications.

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A Study on Electrical Performance of SiC-based Self-switching Diode (SSD) as a High Voltage High Power Device

2023-12-01 , Sha’ari N.Z.A.A. , Nor Farhani Zakaria , Shahrir Rizal Kasjoo , Ahmad M.F. , Mohd Natashah Norizan , Ili Salwani Mohamad , Mohd Fairus Ahmad , Shamsul Amir Abdul Rais , Banu Poobalan , Norhayati Sabani

The Self-switching Diodes (SSDs) have been primarily researched and used in low-power device applications for RF detection and harvesting applications. In this paper, we explore the potential of SSDs in high-voltage applications with the usage of Silicon Carbide (SiC) as substrate materials which offers improved efficiency and reduced energy consumption. Optimization in terms of the variation in the interface charges, metal work function, and doping concentration values has been performed by means of a 2D TCAD device simulator. The results showed that the SSD can block up to 600 V of voltage with an optimum interface charge value of 1013 cm-2, making them suitable for higher voltage applications. Furthermore, it also found that the work function of the metal contact affected the forward voltage value, impacting the current flow in the device. Variation in doping concentrations also resulted in higher breakdown voltages and significantly increased forward current, leading to an increased power rating of 27 kW. In conclusion, the usage of 4H-SiC-based SSDs shows a usable potential for high-voltage applications with optimized parameters. The results from this research can facilitate the implementation of SSD in the development of high-power semiconductor devices for various industrial applications.

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Simulation and characterization of an inverter logic gate by utilizing InGaAs-based planar devices

2023-12 , Faradilla Aziz , Shahrir Rizal Kasjoo , Nor Farhani Zakaria , Fauzi Packeer , A. K. Singh

Electronic circuits known as logic gates can perform basic logical operations like inverters, AND, and OR gates. These logic gates serve as the basis for digital electronics, and they are a common component in various electronic devices, such as computers, smartphones, and other types of digital systems. This research presents an inverter logic gate made of planar devices, which have significantly simpler structures than multi-layered transistors and diodes, namely the self-switching diode (SSD) and side-gated transistor (SGT). The inverter logic gate is realized by simply connecting both SSD and SGT in parallel. The electrical characteristics and performances of the inverter logic gate are assessed based on InGaAs material using SILVACO Inc.'s ATLAS device simulator software. The simulation results show that the functionality of the proposed planar inverter is comparable to that of a conventional inverter logic gate based on the standard truth table of the device. This has demonstrated the feasibility of building logic gates using a combination of SSDs and SGTs. In addition, the planar structure of SSD and SGT allows for a relatively low-cost device fabrication process as well as offering a high-frequency operation due to low parasitic elements in the devices.

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