International Journal of Nanotechnology (19 papers in press)

Regular Issues

• A simulation-based study on the disc brake temperature distribution for optimizing hole geometry
  by Shyam Sunder Sharma, Hariharan Raju, Pranay Singh Tomar, Rajesh Jangid, Rahul Khatri 
  Abstract: Disc brakes used in automotive are responsible for braking to ensure a smooth and safe ride. This study deals with the thermal analysis of a disc brake rotor under various geometry of holes cut on the disc rotor surface. The friction on the disc escapes in the form of heat from the surface of the disc rotor. The temperature observed on the surface of the rotor, because of the friction developed between the brake pads and the rotor is analysed using ANSYS 18.1. The rotor is designed by assuming appropriate parameters in SOLIDWORKS 17. The temperature distribution and total heat flux were observed using ANSYS 18.1. The analysis was carried out on different hole geometries i.e. circular, square, 3/4th circular, straight slots, and rotor without holes. The dissipation of heat was found better in disc rotor with holes as compared to rotor without holes. The simulation study shows that the slotted holes on the disc rotor has surface temperature i.e. 89.356
  Keywords: Automotive disc brake; Simulation; Hole geometry; Heat dissipation.
  
  
• Characteristics of InGaN/AlN heterostructure grown by using MOCVD technique
  by Ahmad Sauffi Yusof 
  Abstract: The tuneable wide direct bandgap (covering a broad range of spectral regions) of III-nitride semiconductors, particularly indium gallium nitride (InGaN), has credited this material as a promising candidate for optoelectronic devices such as solar cells and photodetectors with the ability to have a selective or narrow response. However, developing such a device is not a straightforward process due to phase separation and composition inhomogeneity in InGaN ternary alloy. Thus, it is crucial to rigorously optimize the growth process and carry out an in-depth characterization to suppress those defect formation and obtain a high-quality InGaN active layer, which is suitable for the subsequent device fabrication process. In this work, a series of InxGa1-xNepilayers were epitaxially grown over a commercial 2 AlN/sapphire template using Taiyo Nippon Sanso Corporation (TNSC) metal-organic chemical vapor deposition (MOCVD) system. Then, to study the effect of the indium incorporation process and the correlation with its physical properties, the InxGa1-xNepilayers were grown at a different temperature setting from 860
  Keywords: InGaN; MOCVD; Thin-Film; Characterization; AlN.
  
  
• Effect of GaN Cap Layer Towards Ohmic Contact of Open-Gate Cr AlGaN/GaN High Electron Mobility Transistor
  by Najihah Fauzi 
  Abstract: Metal-organic chemical vapor deposition (MOCVD) was used to grow AlGaN/GaN HEMT on a sapphire substrate with different thicknesses of the GaN cap layer from 1.5 nm to 2.5 nm for open-gate chromium (Cr) AlGaN/GaN HEMT structures. High-resolution X-ray diffraction (HRXRD) was utilized to investigate the structural characteristics of the materials has been investigated. A non-annealing technique is used to reduce the negatively impacted on the electrical properties is bad for the function of the device. The use of the GaN cap layer improved the performance of the devices as the resistance decreased with increasing the thickness of the GaN cap layer. Here we demonstrate the comparison between different thicknesses of GaN cap layers to improve the resistivity of the device.
  Keywords: GaN cap; AlGaN/GaN; HEMT; TLM; ohmic contact.
  
  
• Fabrication ofUltraviolet Photodetector using Au Nanoparticles Decorated ZnO NRs/GaN
  by Shireen Mohammed Abed 
  Abstract: This work focuses on improving the performance of ultraviolet (UV) photodetectors (PDs) based on n-ZnO nanorods (NRs)on Mg-doped- gallium nitride (GaN) through the utilization of surface plasmon resonance (SPR) induced by gold (Au) nanoparticles (NPs). ZnO NRs were grown on a seeded p-GaN substrate, enabling the growth of high-density ZnO nanorods in various orientations. Au NPs were then deposited on the surface of ZnO NRs using a photo-deposition method with pre-prepared Au NPs liquid obtained via laser ablation. ZnO and GaN materials, with their inherent broad bandgap characteristics and unique electrical, optical, and structural features, are commonly employed for creating UV PDs. The defect emission levels in ZnO NRs promote SPR in Au NPs, enhancing the electromagnetic field and facilitating the transfer of electrons across the barrier height at the Au NP/ZnO interface. This results in improved optical and electrical properties on the surface of ZnO NRs. The incorporation of Au NPs enhances the responsivity and sensitivity of ZnO NRs UV photodetectors. The fabricated UV detector, utilizing ZnO NRs array decorated with Au nanoparticles, exhibits highly sensitive and repeatable characteristics, including a high responsivity (R), the highest gain current, and a high external quantum efficiency (EQE) of 43.03 A/W, 7264, and 14621.52%, respectively, under UV light illumination at 365 nm. By employing SPR through Au NPs, this study demonstrates significant enhancements in the performance of UV photodetectors based on ZnO NRs/GaN, contributing to the advancement of visible-blind UV PDs.
  Keywords: Au nanoparticles; ZnO nanorods; Mg doped-GaN; Surface plasmon resonance (SPR); UV photodetectors; photo-deposition method.
  
  
• Laser Synthesis Route for Production of GaN Nanocrystals for Optical Sensor Protection
  by M.A.A. Bakar 
  Abstract: Gallium nitride is a well-known material in optoelectronic field due to its unique structure properties which provide benefit including in optical limiting application. The limitation of optical limiting properties of GaN itself could be expanded by introducing a smaller form factor known as nanocrystals to utilizes the surface/volume ratio for light interaction. Hence, this study will be using an instant and chemical-free technique of synthesizing GaN nanocrystals by using laser ablation. The ablation parameter at varied output energy produces nanocrystals in dimension between 40 to 60 nm which is observed under HRTEM. The presence of GaN in nanocrystals form also confirmed via EDS and AFM. UV-Vis spectroscopy shows peak absorption at wavelength of 299 nm and photoluminescence emission peak at 485 which corelated to the GaN nanocrystals itself. The optical limiting properties of the samples are tested under direct laser irradiation shows reduction in light transmittance from GaN nanocrystals however at slightly different rate for every sample as the input power of incident laser is increased. By further extrapolation, the optical threshold achieved by the GaN nanocrystals is at 857, 707 and 607 mW. This shows that the GaN nanocrystals are successfully synthesized via laser ablation and a viable candidate for optical limiters material for optoelectronic device.
  Keywords: Gallium Nitride; Laser Ablation; Optical Limiting.
  
  
• Analysis of the Influence of the Traps on theAlGaN/GaN MOSHEMT Characteristics for LowLeakage Power Devices
  by N. Islam 
  Abstract: AlGaN/GaN,Metal Oxide Semiconductor High Electron Mobility Transistors (MOSHEMTs) are very attractive for high-power, high-frequency, and high-temperature applications with low gate leakage current. However, charge trapping at the insulator/AlGaN interface is believed to limit the performance of AlGaN/GaN MOSHEMTs. This research investigates the trapping effects of TCAD, device simulation on Silvaco Software. Thus, it is obverse that changing the donor or acceptor traps density with trap energy at the HfAlO/AlGaN interface, which impacts the ID vs. VGS, ID vs. VDS, and Transconductance characteristics curve. Moreover, it also influences the interface charge, 2DEG density, and Threshold Voltage (VTH). On the contrary, varying donor or acceptor trap energy does not illustrate a significant impact on the characteristics curve because both donor and acceptor traps are fully ionized. Eventually, it is summarized that the I vs. V characteristics curve of the AlGaN/GaN, MOSHEMT, is highly influenced by the effective positive charge density at the HfAlO/AlGaN interface.
  Keywords: GaN; MOSHEMT; HEMT; Trap; Density; TCAD; Characteristics Curve; Power devices; Semiconductor devices; Wide bandgap.
  
  
• Investigation into Poly (9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) Coated Zinc Oxide Nanorods on ITO Substrates
  by Suvindraj Rajamanickam 
  Abstract: This work investigates the morphological, structural, optical, and electrical properties of zinc oxide (ZnO) nanorods (NRs) coated with poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) for potential applications in UV photodetectors. ZnO NRs are synthesized using a low-cost hydrothermal method, and PFO is deposited onto the NRs through spin coating. The surface morphology and elemental composition are characterized using field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDX). X-ray diffraction (XRD) analysis confirms the presence of ZnO NRs and the amorphous nature of PFO. The absorption spectra show characteristic peaks related to ZnO NRs and PFO. Current-voltage (I-V) measurements reveal semi-Schottky behaviour for ZnO/Pt contact and p-n diode characteristics for ZnO NRs coated with PFO. The results indicate the formation of a p-n heterojunction between ZnO NRs and PFO, suggesting the potential for enhanced photodetection performance.
  Keywords: PFO polymer; ZnO nanorods; FESEM; UV-vis; I-V characterization.
  
  
• The Effect of Varying Oxidizing Conditions for Transformation of Metallic Cerium to Cerium Oxide Films
  by A.R.M. Zabidi 
  Abstract: A direct current (DC) sputtering technique was conducted to deposit metallic cerium (Ce) films on n-type Si 100) substrates. Post-sputter oxidation at 800
  Keywords: cerium; CeO2; dry oxidation; nitrogen; oxygen; current density.
  
  
• Studies onGa2O3 Thin Films Subjected to Post-Deposition Annealing in Argon Ambient
  by P.H.M.A. Hedei 
  Abstract: The effects ofradio frequency (RF) magnetron sputtered Ga2O3thin filmssubjected todifferent post-deposition annealing temperatures at 400, 600, 800 and 1000 for 60 min in argon ambient were investigated. The grazing incidence X-ray diffraction had discovered that an amorphous Ga2O3thin film was formed during post-deposition annealing at 400. The detection of polycrystalline -Ga2O3phase was observed when the Ga2O3thin filmswere annealed at/beyond 600, wherein an improvement in crystallinity was attained as the post-deposition annealing temperature was increased from 600 to 1000.Nevertheless, the employment of the highest post-deposition annealing temperature at 1000 has triggered an excessive diffusion of oxygen anions to the interfacecontributing to the formation of the thickest SiO2interfacial layer. It was determined that Ga2O3thin film annealed at 1000 had attained the lowest leakage density when compared with the Ga2O3thin films annealed at lower temperatures.
  Keywords: Gallium oxide; Silicon; Sputtering; Grazing incidence X-ray diffraction; Annealing.
  
  
• Energy Band Gap Investigation of Al Nanoparticles/Polystyrene Nanocomposite Foils
  by H. Naser 
  Abstract: In this work, polystyrene/aluminium (PS/Al) nanocomposites were fabricated based on the various concentrations (0, 1, 5, 10, and 15 mg) of Al nanoparticles using the casting method. The UV-Visible absorption spectra of PS/Al nanocomposites as foils, the trend of pure PS, and the resulting PS/Al nanocomposites were all investigated. The neat PS polymer did not show any peak in the absorption spectra. However, the resulting absorption of PS/Al increased with the Al nanoparticles nanofillers. All samples had their energy band gap determined. The results show a decreasing energy band gap from 4.40 to 3.7 eV as the concentrations of Al nanoparticles are increased.
  Keywords: Aluminium energy gap; linear absorption coefficient; nanocomposites; polystyrene.
  
  
• Effects of Post-Deposition Annealing in Argon-Oxygen-Argon Ambient on Physical and Electrical Characteristics of Thulium Oxide Passivation Layer on Silicon Substrate
  by Junchen Deng 
  Abstract: The thulium oxide (Tm2O3) passivation layer was deposited on silicon substrate via radio frequency magnetron sputtering and then subjected to different post-deposition annealing in argon-oxygen-argon ambient at 500, 600, 700, and 800
  Keywords: Thulium oxide; metal-oxide-semiconductor; passivation layer; annealing; argon.
  
  
• Effect of Post-Deposition Annealing on CeO2 Passivation Layer Spin Coated on Silicon Substrate in Nitrogen Ambience
  by Kammutty Musliyarakath Abdul Shekkeer 
  Abstract: The metal-organic decomposed cerium oxide (CeO2) precursor was deposited on a silicon (Si) substrate using the spin coating technique. The as-deposited CeO2 passivation layer was subjected to post-deposition annealing at 600, 700, 800, and 900oC for 30 min in nitrogen ambience. The employment of nitrogen ambience was effective in minimising the formation of interfacial layer by acting as a nitrogen diffusion barrier layer at the interface. The CeO2 passivation layer annealed at 800oC has achieved a lower leakage current density and the highest electric breakdown field due to the passivation of interface defects by nitrogen ions. The detailed study of physical and electrical characteristics of the investigated CeO2 passivation layers on Si substrate was reported in this work.
  Keywords: Cerium oxide; Silicon; MOS capacitor; Nitrogen; Annealing.
  
  
• Numerical Study on the Optimization of AlGaN-based Deep Ultra-Violet Light Emitting Diodes Single Quantum Wells
  by M. Mazwan 
  Abstract: Solid-state ultra-violet light emitting diodes (UV-LEDs) based on aluminum gallium nitride (AlGaN) semiconductors have drawn considerable attention because their energy can be tuned from 3.4 eV (GaN) to 6.2 eV (AlN) by changing Al content. Subsequently, AlGaN-based UV-LEDs with a full wavelength coverage of UV spectral range (400200 nm) can be fabricated. However, their external quantum efficiency, especially the deep UV-LEDs, is still much lower than commercially available blue LEDs. To improve the efficiency of the AlGaN-based deep UV-LEDs, the effects of the thicknesses, pairings, and Al composition of quantum wells (QWs) are examined using self-consistent simulation software. The normalized simulation results show that the emission wavelength is blue shifted as the Al composition increased in single quantum well UV-LEDs. The simulation also assessed the effect of single quantum wells (SQWs) configuration and discovered that changing the SQWs' thickness leads to considerable variance in device power in a log scale.
  Keywords: Quantum well; aluminum gallium nitride; deep ultra-violet; light emitting diodes; self-consistent simulation software.
  
  

Special Issue on: Smart Bio-Signal Acquisition System

• Intelligent overlay algorithm for medical data management based on wireless communication technology and feature fusion  
  by Changrong Peng, Xiaodong Zhang, Qian Liu, Xiaofang Zhao, Chenyang Dai 
  Abstract: Medical data management through wireless communication system become essential to make data available at all time. To address the problem of poor quality of management, a intelligent overlay algorithm based on wireless communication technology and feature fusion is proposed. The algorithm first uses sensors remote sensing equipment to collect patient data and transmit them by wireless communication, followed by image and data filtering, then feature extraction and feature fusion, and finally seamless overlaying by projection model. The results show that the spatial frequency and average gradient of the superimposed patient data management meets the requirements, indicating that the resultant data after the application of the sensing data is superimposition algorithm based on wireless communication technology and feature fusion retain the detail components of the patient data more realistically, with good clarity, and the image information is better maintained.
  Keywords: wireless communication technology; feature fusion; medical data; sensors; intelligent overlay algorithm.
  
  
• Evaluation method for colour matching using artificial intelligence technology  
  by Lijuan Yao, Ling Tang 
  Abstract: The existing colour matching evaluation methods have the problem of fuzzy colour attributes, which leads to high image distortion. This paper designs an evaluation method of public space indoor landscape colour matching based on artificial intelligence technology. The method quantifies the colour layout of the public space, determines the main colour of the space, identifies the colour attributes of the indoor landscape, deploys the combined colour phase ring, uses artificial intelligence technology to extract the colour matching features, calculates the colour distance combined with the transition colour frequency information, and adopts the colour quantisation algorithm to set the evaluation model. The experiment results show that the average distortions of the evaluation method and the other two evaluation methods is 30.12, 38.96, are 38.87, respectively, which proves that the colour matching evaluation method combined with artificial intelligence technology has higher use value.
  Keywords: artificial intelligence technology; colour layout; colour matching; evaluation method; public space; interior landscape;.
  
  
• Stereoscopic display of architectural design images based on virtual reality technology  
  by Ling Tang, Lijuan Yao 
  Abstract: The current image stereoscopic display method mainly displays images stereoscopically from the perspective of human left and right eye visual imaging, which not only displays images with distortion and missing details, but also makes it difficult to realise interaction for complex image stereoscopic display. This paper proposes a stereoscopic display method of architectural design images based on virtual reality technology. The images are drawn using DIBR technology and the depth images are processed using Gaussian filtering and so on. After designing the virtual interaction of the image stereoscopic display scene, EON is used to analyse the lighting of the building exterior and realise the stereoscopic display of the image. The simulation experimental data of the stereoscopic display method show that the proposed image stereoscopic display method relatively improves the display effect by about 66.7% and has good adaptability for different grey value images.
  Keywords: architectural exterior; design images; image presentation; stereoscopic presentation; virtual interaction; virtual reality technology.
  
  
• Network security analysis of diseases reporting in wireless sensor networks  
  by Zhang Yanling, Zhang Ting 
  Abstract: In order to solve the problem of low security in the process of direct reporting of traditional infectious diseases like ring worm, chicken pox, flu, cold etc, the corresponding network direct report security model is established by wireless communication technology. On this basis, the security risk level of wireless communication network is divided. This paper analyses the negative factors that affect network security from hacker attack, high risk vulnerability of software and user information tampering. Combined with the analysis results of multiple security mechanisms of the direct report network of infectious diseases, the quantitative evaluation of network security is realized, that is, the modelling and analysis of the network direct report security of infectious diseases is realized. Compared with traditional security model, it is found that the network direct report security model can reduce the loss and error of infectious disease data, which has a high application value. The proposed work computes less error rate of minimum 0.04 MB to maximum 0.14 MB. This error data is very less when compared to traditional techniques.
  Keywords: direct epidemic reporting; epidemic network; infectious diseases; security model; wireless communication technology.
  
  
• Deep learning-based feature extraction coupled with multi-class SVM for COVID-19 detection in the IoT era  
  by Auwalu Mubarak, Sertan Serte, Fadi Al-Turjman, Rabiu Aliyu, Zubaida Said, Mehmet Ozsoz 
  Abstract: The deadly coronavirus virus (COVID-19) was confirmed as a pandemic by the World Health Organisation (WHO) in December 2019. Prompt and early identification of suspected patients is necessary to monitor the transmission of the disease, increase the effectiveness of medical treatment and as a result, decrease the mortality rate. The adopted method to identify COVID-19 is the Reverse-Transcription Polymerase Chain Reaction (RT-PCR), the method is affected by the shortage of RT-PCR kits and complexity. Medical imaging using deep learning has proved to be one of the most efficient methods of detecting respiratory diseases, but efficient deep learning architecture and low data are affecting the performance of the deep learning models. To detect COVID-19 efficiently, a deep learning model based feature extraction coupled with Support Vector Machine (SVM) was employed in this study, Seven pre-trained models were employed as feature extractors and the extracted features are classified by multi-class SVM classifier to classify CT scan images from COVID-19, common pneumonia and healthy individuals. To improve the performance of the models and prevent overfitting, training was also carried out on augmented images. To generalise the model's performance and robustness, three datasets were merged in the study. The model with the best performance is the VGG19 which was trained with augmented images: it achieved an accuracy of 96%, a sensitivity of 0.936, a specificity 0f 0.967, an F1 score of 0.935, a precision of 0.934, a Yonden Index of 0.903 and AUC of 0.952. The best model shows that COVID-19 can be detected efficiently on CT scan images.
  Keywords: artificial intelligence; COVID-19; SVM; feature extraction.
  DOI: 10.1504/IJNT.2021.10040115
   
  

Special Issue on: Eco-Friendly and Sustainable Cognitive Green Nano-Technologies for the Mitigation of Emerging Environmental Pollutants

• Preparation of titanium dioxide composite nanomaterials using copper catalysis and their dynamic adsorption and photocatalytic performance in water treatment  
  by Ye Tian 
  Abstract: The aim is to investigate the dynamic adsorption performance of titanium dioxide (TiO2) nanocomposite materials in water treatment, providing direction for water purification. The copper-catalysed living free-radical polymerization method polymerizes the prepared TiO2 particles with tertiary amine polymer to manufacture the TiO2 polymer nanocomposite materials. The prepared TiO2 nanocomposite materials are then modified to obtain the quaternised TiO2 polymer nanocomposite materials (quaternised TiO2@poly(DEAEMA)), which are characterized and analysed. Finally, the water treatment performance of quaternised TiO2@poly(DEAEMA) is judged through photocatalysis and adsorption experiments, while the antibacterial performance of the prepared materials is judged using the common Escherichia coli and Staphylococcus aureus. Results demonstrate that the quaternised TiO2@poly(DEAEMA) polymer nanocomposite materials are completely and tightly wrapped, presenting a flower-like appearance, with a significantly-increased diameter and an average size of about 600nm, which can be utilized as the pollutant adsorbent. Water treatment simulation reveals the fastest adsorption rate and the highest adsorption capacity of quaternised TiO2@poly(DEAEMA), reaching 265 mg/g given the same reaction time. The catalytic removal rate in ultraviolet and visible light reaches 94%, and the photocatalysis of visible light reaches 69%. Until the reaction lasts for 45 minutes, its antibacterial activity is optimal, and the diameter of the inhibition zone against Escherichia coli and Staphylococcus aureus exceeds 16 mm. Therefore, the prepared TiO2 nanomaterials have high adsorption properties, good photocatalysis performance, and excellent antibacterial properties, which can provide an experimental basis for the treatment and purification of water resources in the industry.
  Keywords: titanium dioxide; water treatment; dynamic adsorption; photocatalysis; nanocomposite material.