Mohd Khairuddin Md Arshad
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Preferred name
Mohd Khairuddin Md Arshad
Official Name
Mohd Khairuddin , Md Arshad
Alternative Name
Md. Arshad, M. K.
Arshad, Mohd K.M.
Arshad, M. K.M.
Khairuddin Md Arshad, Mohd
Arshad, M. K.Md
Main Affiliation
Scopus Author ID
57211870224
Researcher ID
L-5830-2013

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  • Publication
    Field-Effect Transistor-based Biosensor Optimization: Single Versus Array Silicon Nanowires Configuration
    ( 2020-01-01)
    Ong C.C.
    ;
    Mohamad Faris Mohamad Fathil
    ;
    Mohd Khairuddin Md Arshad
    ;
    Mohammad Nuzaihan Md Nor
    ;
    Ruslinda A. Rahim
    ;
    Uda Hashim
    ;
    Rafizatul Fitri Abdullah
    ;
    Mohd Hazmi Mohd Ghazali
    ;
    Tamjis N.
    This paper demonstrated the effect of different number of silicon nanowire transducer channels, in other word single, double, and triple channels towards the performance of field-effect transistor-based biosensor through simulation tool. These silicon nanowire field-effect transistor biosensors were designed and simulated in device simulation modelling tool, Silvaco ATLAS with fixed length, width, and height of the silicon nanowire. Different negatively interface charge density values were applied on the transducer channels’ surface of the biosensors to represent as detected target biomolecules that will bind onto the surface of the transducer regions. Based on the results, more negatively interface charges density values presented on the sensing channels had reduced the electron carrier accumulation at the channel’s interface, therefore, reduced drain current flow between the source and drain terminal. With the increase number of the transducer channels, significant change in drain current for every applied negatively interface charges became more apparent and increased the sensitivity of the biosensor. The triple transducer channels silicon nanowire field-effect transistor biosensor had demonstrated highest sensitivity, that is 2.83 µA/e∙cm2, which indicates it has better response for the detection of interface charges, thus increases chances for transducer channels reaction to the target biomolecules during testing or diagnosis.
  • Publication
    Impact of buried oxide thickness in substrate-gate integrated silicon nanowire field-effect transistor biosensor performance for charge sensing
    ( 2021-07-21)
    Tan Y.M.
    ;
    Mohamad Faris Mohamad Fathil
    ;
    Mohammad Nuzaihan Md Nor
    ;
    Norhayati Sabani
    ;
    Teoh X.Y.
    ;
    Mohd Khairuddin Md Arshad
    ;
    Subash Chandra Bose Gopinath
    ;
    Rahman S.F.A.
    ;
    Uda Hashim
    The paper investigated on performance in charge sensing for substrate-gate integrated silicon nanowire field-effect transistor biosensor at different thickness of the buried oxide layer, sandwiched in between the top-silicon and substrate layers. The device structures with different buried oxide thickness ranging from 100 to 200 nm were designed and simulated using the Silvaco ATLAS device simulation software. The increase of buried oxide thickness reduced the strength of induced electric field that contributes to the formation of inversion layer for current flow through the silicon nanowire channel, hence contributed to the increase in threshold voltage. For simulation of charge sensing, the device demonstrated the ability to identify different interface charge values ranging from -5×1010 to -9×1010 e· cm-2 applied on the surface of the silicon nanowire channel to represent target charge biomolecules that bound to the biosensor in actual detection. Significant change in threshold voltage can be observed due to the applied interface charge density values and was evaluated to determine the sensitivity for charge sensing performance. The device shows better performance when designed with buried oxide thickness of 200 nm at sensitivity of 1.151 V/e· cm-2.
  • Publication
    Polysilicon nanowire with liquid gate control for pH sensing
    (Universiti Malaysia Perlis (UniMAP), 2018-12)
    Mohammad Nuzaihan Md Nor
    ;
    M. F. Farizal
    ;
    C. W. Chung
    ;
    M. N. Aziz
    ;
    Mohamad Faris Mohamad Fathil
    ;
    C. Ibau
    ;
    S. Johari
    ;
    Mohd Khairuddin Md Arshad
    Polysilicon nanowire based sensors have garnered great potential in serving as highly sensitive, label-free and real-time sensing for broad range of applications, that include but not limited to pH values, DNA molecules, proteins and single viruses. In this research, two distinct types of polysilicon nanowires are fabricated, one has an array of nanowires with a 100 nm width and the other is a single nanowire with 100 nm width. Top-down fabrication method is utilized to fabricate the polysilicon nanowire from silicon wafer using the conventional photolithography and reactive ion etching processes. The fabricated polysilicon nanowire have an approximately 100 nm in width, is then undergo surface modification, which is the nanowire is immersed into a 2% 3-aminopropyltriethoxysilane (APTES) to create a molecular binding chemistry, which results in amino (NH2) and silanol (SiOH) groups at the nanowire surface. Since the surface of the polysilicon is hole-dominated (p-type material), it responds well to changes in pH values. In this research, pH sensing is performed based on several types of standard aqueous pH buffer solutions (pH 2, pH 4, pH 7, pH 10 and pH 12) to demonstrate the electrical response of the sensor. At low pH, NH2 group is protonated, resulting in high proton ion acts as a positive gate. At high pH, SiOH group is deprotonated, resulting in bringing negative charges at the polysilicon nanowire surface and acts as a negative gate voltage. The sensitivity of the polysilicon nanowire attained was 207.1 fS/pH for array nanowire and 8.91 fS/pH for single nanowire, which shows excellent properties for pH sensing.
  • Publication
    Design and simulation of Cylindrical Stacked Silicon Nanowire (SiNW) field-effect transistors
    (IEEE, 2023-12)
    H’ng Chee Chang
    ;
    Mohd Khairuddin Md Arshad
    ;
    Mohamad Faris Mohamad Fathil
    ;
    Mohammad Nuzaihan Md Nor
    ;
    Subash Chandra Bose Gopinath
    ;
    Ramzan Mat Ayub
    In continuous effort to increase the current drive without sacrificing the off current and better off gate control on the channel, the MOSFET devices have advanced from classical, planar, single-gate and three-dimensional devices with multi-gate structures. Recently, multi-bridge-channel technology has become a feasible solution beyond FinFET multi-gate structure. In this work, we design Gate-All-Around (GAA) based on silicon nanowire. Numerical simulation based Silvaco Device tools has been used to design multiple number of cylindrical nanowires, then followed by different channel diameter, consisting of 20, 30 and 40 nm. The devices are the characterized on transconductance, threshold voltage, DIBL and subthreshold slope. The simulation results indicate that the device performance is best at a nanowire diameter of 20 nm due to improved gate control over charge distribution. Regarding the number of nanowires, the voltage performance is not significantly affected by Nnw =1 or higher. However, higher numbers of nanowires, such as Nnw = 3, demonstrate improved drain current and transconductance.
  • Publication
    Top-Down Fabrication of Silicon Nanogap for Detection of Dengue Virus (DENV)
    ( 2020-01-01)
    Zulkiffli M.N.F.
    ;
    Mohammad Nuzaihan Md Nor
    ;
    Mohamad Faris Mohamad Fathil
    ;
    Zailan Z.
    ;
    Isa N.A.M.
    ;
    Ibau C.
    ;
    Zainol Abidin W.’.B.
    ;
    Azlan A.S.
    ;
    Mohd Khairuddin Md Arshad
    In this work, a highly sensitive Silicon nanogap biosensor was demonstrated for Deoxyribonucleic acid (DNA) detection related to Dengue virus (DENV). The Silicon nanogap was fabricated using the top–down conventional lithography approach followed by reactive ion etching (RIE) to further thin down the nanogap. The inspections of Silicon nanogap structures were carried out using the scanning electron microscope (SEM) and atomic force microscopy (AFM). The surface of the fabricated Silicon nanogap was functionalized by means of a three-steps procedure involving surface modification, immobilization and hybridization. This procedure acts as a liquid gate control to establish the electrical detection targets of the dengue virus. The electrical detection is based on the changes in the current of the sensor due to the accumulation of the negative charges by the immobilized probe and hybridized target Deoxyribonucleic acid. The limit of detection (LOD) achieved was recorded at 10 pM with a 207 nm of fabricated Silicon nanogap and its sensitivity at 1.5 × 10−10 AM−1. The demonstrated results show that the Silicon nanogap has the excellent properties for detection of dengue virus as biosensor devices.
      38  3
  • Publication
    Fabrication and simulation of silicon nanogaps pH sensor as preliminary study for Retinol Binding Protein 4 (RBP4) detection
    (Universiti Malaysia Perlis (UniMAP), 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.
      3  21
  • Publication
    Immunosensing prostate-specific antigen: Faradaic vs non-Faradaic electrochemical impedance spectroscopy analysis on interdigitated microelectrode device
    ( 2020-11-01)
    Ibau, Conlathan
    ;
    Mohd Khairuddin Md Arshad
    ;
    Mohammad Nuzaihan Md Nor
    ;
    Subash Chandra Bose Gopinath
    ;
    Mohamad Faris Mohamad Fathil
    ;
    Shahidah Arina Shamsuddin
    This work explores Electrochemical Impedance Spectroscopy (EIS) detection for a highly-sensitive quantification of prostate-specific antigen (PSA) in Faradaic (f-EIS) and non-Faradaic modes (nf-EIS). Immobilization of monoclonal antibody specific to PSA (anti-PSA) was performed using 1-ethyl-3-dimethylaminopropylcarbodiimide hydrochloride and N-hydroxysuccinimide crosslinking agents in order to conjugate carboxylic (-COOH) terminated group of 16-Mercaptoundecanoic acid with amine (-NH3+) on anti-PSA epitope. This approach offers simple and efficient approach to form a strong, covalently bound thiol-gold (S–Au) for a reliable SAM layer formation. Studies on the topographic of pristine Au-IDE surface were performed by Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy techniques, meanwhile a 3-dimensional optical surface profiler, Atomic Force Microscopy and X-ray Photoelectron Spectroscopy techniques were used to validate the successful functionalization steps on the sensor transducer surface. Detection of PSA in f-EIS mode was carried out by measuring the response in charge transfer resistance (Rct) and impedance change (Z), meanwhile in nf-EIS mode, the changes in device capacitance was monitored. In f-EIS mode, the sensor reveals a logarithmic detection of PSA in a range of 100 ng/ml down to 0.01 ng/ml in Phosphate Buffered Saline with a recorded sensitivity of 2.412 kΩ/log10 ([PSA] ng/ml) and the limit of detection (LOD) down to 0.01 ng/ml. The nf-EIS detection mode yields a logarithmic detection range of 5000 ng/ml down to 0.5 ng/ml, with a sensitivity of 8.570 nF/log10 ([PSA] ng/ml) and an LOD of 0.5 ng/ml. The developed bio-assay yields great device stability, specificity to PSA and repeatability of detection that would pave its way for the future development into portable lab-on-chip bio-sensing system.
      10  27
  • Publication
    Numerical simulation on the impact of back gate voltage in thin body and thin buried oxide of silicon on insulator (SOI) MOSFETs
    ( 2023-10)
    K.Y Koay
    ;
    Mohamad Faris Mohamad Fathil
    ;
    Mohammad Nuzaihan Md Nor
    ;
    Ramzan Mat Ayub
    ;
    Mohd Khairuddin Md Arshad
    Silicon-on-Insulator (SOI) technology provides a solution for controlling Short-Channel Effects (SCEs) and enhancing the performance of Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs). However, scaling down SOI MOSFETs to a nanometer scale does not necessarily yield further scaling benefits. Introducing multiple gates, such as a double gate configuration, can effectively mitigate SCEs. Nonetheless, fabricating a flawless double gate structure is an exceedingly challenging endeavor that remains unrealized. The adoption of a back gate bias, with an asymmetrical thickness arrangement between the front and back gates, mimicking the behavior of a double gate, offers an alternative approach. This approach has the potential to modify the electrical characteristics of the device, thus potentially leading to improved control over SCEs. In this study, we employed 2D simulations using Atlas to investigate the influence of back gate biases, namely, -2.0 V, 0 V, and 2.0 V on a 10 nm silicon thickness at the top and a 20 nm buried oxide thickness for n-channel MOSFETs. We focused on key parameters, including threshold voltage (VTh), Drain Induced Barrier Lowering (DIBL), and Subthreshold Swing (SS). The results demonstrate that a negative back gate bias is the most favorable configuration, as it yields superior performance. This translates into more effectively controlled SCEs across all the parameters of interest.
      1  7
  • Publication
    The impact of silicon nanowire transducer channel width on field-effect transistor biosensor performance
    ( 2021-05-03)
    Abdullah R.F.
    ;
    Mohamad Faris Mohamad Fathil
    ;
    Mohd Khairuddin Md Arshad
    ;
    Mohammad Nuzaihan Md Nor
    ;
    Subash Chandra Bose Gopinath
    ;
    Uda Hashim
    ;
    Ong C.C.
    ;
    Tamjis N.
    ;
    Ghazali M.H.M.
    This paper reported on performance assessment of a field-effect transistor-based biosensor with different widths of the silicon nanowire transducer channel. Silvaco ATLAS device simulation software was used to model the device design with three different channel widths, which are 100, 150, and 200 nm. In this simulation, the bounded target biomolecules during actual detection using the biosensor were represented by several negative interface charge density values applied on the surface of the transducer channel. Increase in accumulation of hole carriers beneath the channel's surface was observed due to the availability of negative interface charges on the surface, hence increased the output drain current. Furthermore, width reduction of the device's channel had allowed more significant change in drain current due to application of different interface charge density values and increased the device's sensitivity. Among the simulated devices, silicon nanowire field-effect transistor-based biosensor with transducer channel width of 100 nm had shown highest sensitivity (-56.45 nA/e.cm2) with lowest interface charge density detection (2.79u1010 e/cm-2), which means it enhances the interface charge detection by providing better response and allows lower limit of detection. Therefore, in actual detection, possibility for reaction of the transducer channel to the specific target biomolecule can be increased.
      1  19
  • Publication
    Electrical simulation on silicon nanowire field-effect transistor biosensor at different substrate-gate voltage bias conditions for charge detection
    ( 2022-12)
    X.Y. Teoh
    ;
    Mohamad Faris Mohamad Fathil
    ;
    Y.M.Tan
    ;
    Norhayati Sabani
    ;
    Mohammad Nuzaihan Md Nor
    ;
    Mohd Khairuddin Md Arshad
    ;
    Ruslinda A. Rahim
    ;
    Nur Hamidah Abdul Halim
    ;
    Ramzan Mat Ayub
    ;
    Uda Hashim
    ;
    M.M. Ibrahim
    In this work, the impact of different substrate-gate voltage bias conditions (below and above the device threshold voltage) on current-voltage characteristics and sensitivity of a silicon nanowire field-effect transistor (SiNW-FET) biosensor was investigated. A 3-dimensional device structure with n-type SiNW channel and a substrate gate electrode was designed and electrically simulated In the Silvaco ATLAS. Next, the SiNW channel was covered with a range of interface charge density to mimic the charged target biomolecule captured by the device. The outcome was translated into a drain current versus interface charge semi-log graph and the device sensitivity was calculated using the linear regression curve’s slope of the plotted data. The device’s electrical characteristic shown higher generation of output drain current values with the increase of negative substrate-gate voltage bias due to the hole carriers’ accumulation that forms a conduction channel in the SiNW. Application of higher negative interface charge density increased the change in drain current, with the device biased with higher substrate-gate voltage shows more significant change in drain current. The device sensitivity increased when biased with higher substrate-gate voltage with highest sensitivity is 75.12 nA/dec at substrate-gate voltage bias of –1.00 V.
      3  62