Article
Physics, Multidisciplinary
Xiao Wang, Yu-Min Zhang, Yu Xu, Zhi-Wei Si, Ke Xu, Jian-Feng Wang, Bing Cao
Summary: In this study, a large-area freestanding GaN layer was successfully separated from a specific structure of Fe-doped GaN substrate through an electrochemical liftoff process, simplifying the preparation process and potentially reducing costs.
Article
Physics, Applied
T. Hamachi, T. Tohei, Y. Hayashi, M. Imanishi, S. Usami, Y. Mori, N. Ikarashi, A. Sakai
Summary: The study investigated the propagation behavior of threading dislocations (TDs) in Na-flux-grown GaN and commercially available HVPE-grown GaN, revealing a correlation between TD morphology and Burgers vectors. Unique TDs with specific Burgers vectors were observed using advanced electron diffraction techniques. The inclinations of TDs were affected by the crystal structure, leading to different morphologies in different types of HVPE-grown GaN crystals.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Crystallography
Yun Lai, Ding Wang, Qinhao Kong, Xiaoju Luo, Jinfeng Tang, Rensuo Liu, Fei Hou, Xianying Wang, Troy J. Baker
Summary: Four-inch semi-insulating free-standing gallium nitride (GaN) wafers grown by hydride vapor phase epitaxy (HVPE) with carbon doping were obtained through a self-separated process. The as-grown wafer thickness can reach 900 mu m without cracks, and x-ray diffraction rocking curves show low FWHMs. The measured resistivity was greater than 10(10) Omega-cm.
JOURNAL OF CRYSTAL GROWTH
(2021)
Article
Physics, Multidisciplinary
Jiafan Chen, Jun Huang, Didi Li, Ke Xu
Summary: This study reports the successful growth of porous AlN films on C-face SiC substrates by HVPE. The influences of growth condition on surface morphology, residual strain, and crystalline quality of AlN films have been investigated. It was found that under the medium V/III ratio growth condition, porous and crack-free AlN films can be obtained.
Article
Physics, Applied
Kazuki Ohnishi, Seiya Kawasaki, Naoki Fujimoto, Shugo Nitta, Hirotaka Watanabe, Yoshio Honda, Hiroshi Amano
Summary: A vertical GaN p(+)-n junction diode with an ideal breakdown voltage was successfully grown by halide vapor phase epitaxy (HVPE). The steep p(+)-n interface was observed and no Si-accumulating layer was formed due to continuous growth. This method offers improved electrical properties compared to regrowth of p-type GaN layers, with a minimum ideality factor of approximately 1.6.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Caroline E. Reilly, Nirupam Hatui, Thomas E. Mates, Shuji Nakamura, Steven P. DenBaars, Stacia Keller
Summary: This research explores the growth of AlN at temperatures below 550 degrees C via MOCVD using a flow-modulated epitaxy scheme, investigating the morphological, compositional, and electronic properties of the films. The study reveals high sheet charges and mobilities for two dimensional electron gases formed at the interface between the low temperature grown AlN layers and the high temperature deposited semi-insulating GaN base layers. Despite low growth temperatures, unintentional gallium incorporation is observed in nominally pure AlN barrier layers near the GaN interface. These results pave the way for the integration of nitride-based electronics on temperature sensitive substrates via epitaxy-based schemes.
APPLIED PHYSICS LETTERS
(2021)
Article
Energy & Fuels
Jacob T. Boyer, Kevin L. Schulte, Matthew R. Young, Aaron J. Ptak, John Simon
Summary: This study reports the development of AlInP-passivated solar cells grown by dynamic hydride vapor-phase epitaxy (D-HVPE). The device performance of AlInP-passivated solar cells was compared with control cells passivated with GaInP. The addition of AlInP passivation improved the current collection and the open-circuit voltage of the solar cells. It is expected that with further optimization, the hydride vapor-phase epitaxy (HVPE)-grown device efficiencies will reach parity with state-of-the-art devices grown by other epitaxial methods.
PROGRESS IN PHOTOVOLTAICS
(2023)
Article
Crystallography
Kazuki Ohnishi, Yuki Amano, Naoki Fujimoto, Shugo Nitta, Hirotaka Watanabe, Yoshio Honda, Hiroshi Amano
Summary: This study investigated the electrical properties and structural defects of p-type GaN layers with different Mg doping concentrations grown by HVPE. It was found that high Mg doping concentrations lead to a decrease in hole concentration and the formation of pyramidal inversion domains (PIDs). Energy-dispersive X-ray spectroscopy showed that Mg atoms accumulate in PIDs, inhibiting the increase in acceptor concentration.
JOURNAL OF CRYSTAL GROWTH
(2021)
Article
Chemistry, Physical
Anna K. Braun, Jacob T. Boyer, Kevin L. Schulte, William E. McMahon, John Simon, Allison N. Perna, Corinne E. Packard, Aaron J. Ptak
Summary: A single-junction GaAs solar cell with 24% efficiency is achieved by directly growing it on a faceted, spalled (100) GaAs substrate using in situ planarization growth with hydride vapor phase epitaxy (HVPE). Controlled spalling and HVPE planarization offer a low-cost method for substrate reuse and enable the direct use of spalled substrates without costly polishing steps. This work demonstrates the viability of controlled spalling coupled with HVPE planarization for lowering the cost of III-V photovoltaics.
ADVANCED ENERGY MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Lei Liu, Ruixian Yu, Guodong Wang, Mingsheng Xu, Shouzhi Wang, Hongdi Xiao, Xiaobo Hu, Lei Zhang, Xiangang Xu
Summary: A self-standing porous GaN crystal film was fabricated for the first time using a high-temperature annealing method, showing reduced stress and improved crystal quality. The theoretical calculations and experimental results demonstrate the potential of high-temperature annealing porous templates for growing high-quality GaN crystals.
Article
Materials Science, Ceramics
Qi Zhanguo, Liu Lei, Wang Shouzhi, Wang Guodong, Yu Jiaoxian, Wang Zhongxin, Duan Xiulan, Xu Xiangang, Zhang Lei
Summary: Compared with previous generations, third generation semiconductor materials, such as gallium nitride (GaN), have superior properties and wide applications in electronic devices, optoelectronics, and power devices. The hydride vapor phase epitaxy (HVPE) method is a promising approach for growing high-quality GaN crystals. However, unintentionally doped GaN obtained by this method shows n-type electrical properties, limiting its use in high-frequency and high-power devices. Doping is a common method to improve the electrical performance of GaN, and this article introduces the structure, properties, and recent advancements in HVPE-grown GaN crystals, as well as the doping characteristics and types, growth process, and the impact of dopants on the electrical properties of GaN. The challenges and opportunities for the HVPE method to grow doped GaN crystals are also discussed.
JOURNAL OF INORGANIC MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Lei Liu, Xu Zhang, Shouzhi Wang, Guodong Wang, Jiaoxian Yu, Xiaobo Hu, Qingjun Xu, Xiangang Xu, Lei Zhang
Summary: This study investigates the growth behavior of GaN on porous substrates during the nucleation stage, revealing that the porous structure reduces dislocations and relieves stress. The findings have important reference value for the growth of GaN crystals on porous substrates.
Article
Materials Science, Multidisciplinary
Hee Ae Lee, Jae Hwa Park, Joo Hyung Lee, Seung Hoon Lee, Hyo Sang Kang, Seong Kuk Lee, Won Il Park, Sung Chul Yi
Summary: The study found that GaN surface can undergo thermal decomposition and oxidation under different thermal treatment conditions, with 900 degrees C annealing for 3 hours being the most effective in releasing internal residual stress and ensuring the best crystal quality.
ELECTRONIC MATERIALS LETTERS
(2021)
Article
Crystallography
Lin Zhang, Zeren Wang, Jiejun Wu, Tong Han, Fang Liu, Xingyu Zhu, Tongjun Yu
Summary: In this study, high quality semi-polar GaN layers were fabricated on m-plane sapphire templates using vertical hydride vapor phase epitaxy system. The in-plane epitaxial relationships between GaN and sapphire substrate were determined, and the crystalline anisotropies were shown to be associated with crystal quality and surface defects.
JOURNAL OF CRYSTAL GROWTH
(2022)
Article
Materials Science, Multidisciplinary
Min Joo Ahn, Kyu-yeon Shim, Woo Seop Jeong, Seongho Kang, Hwayoung Kim, Dae-sik Kim, Junggeun Jhin, Jaekyun Kim, Dongjin Byun
Summary: In this study, a polished plateau-patterned sapphire substrate (PP-PSS) was developed for the epitaxial growth of stress-free GaN microrods. By adjusting the polishing time, selective growth of GaN microrods was achieved on the plateau region of the substrate. The growth mechanism and crystal structure of the GaN microrods were characterized, confirming the feasibility of stress-free epitaxial growth on PP-PSS.
Article
Materials Science, Ceramics
Jolly Jacob, Kashif Javaid, Nasir Amin, Adnan Ali, Khalid Mahmood, Salma Ikram, Muhammad Imran Arshad, Asad Munir, Mongi Amami
Summary: Lanthanum (La3+) substituted Mg-Cd-Bi ferrite nanoparticles were synthesized and their microstructural and electrical properties were investigated. The samples were characterized by XRD, FTIR, SEM, and I-V analyzer. It was found that the samples retained perovskite BiFeO3 phase with distorted rhombohederal structure. The conductivity in La3+-doped ferrite series originated from the hopping of electrons between ions of the same elements, resulting in reduced electrical resistivity and a semiconductor nature.
CERAMICS INTERNATIONAL
(2023)
Article
Materials Science, Ceramics
Muhammad Arshad, Muhammad Azhar Khan, Ghulam Abbas Ashraf, Khalid Mahmood, Muhammad Imran Arshad
Summary: A series of (Zr-Co) substituted Y-type polycrystalline hexaferrite were fabricated by sol-gel auto combustion method, and their structural and electrical properties were investigated. The addition of Zr4+-Co2+ metal cations resulted in an increase in lattice parameters and a decrease in grain size. The formation of pure single-phase Y-type hexaferrites was confirmed by X-ray powder diffraction and FTIR spectra. The electrical resistivity, dielectric properties, and complex impedance spectroscopy indicated that the substitution of Zr4+-Co2+ ions significantly influenced the conduction and dielectric behavior of the nano ferrite materials.
CERAMICS INTERNATIONAL
(2023)
Article
Chemistry, Physical
Kiran Mehmood, Atta Ur Rehman, Nasir Amin, N. A. Morley, Muhammad Imran Arshad
Summary: Spinel ferrites are important due to their low cost, easy preparation, and outstanding electrical, dielectric, and magnetic properties. Graphene nanoplatelets (GNPs) are an excellent supporting material for composites. The NCNF/2.5 wt%GNPs composite prepared by SGAC route showed improved dielectric characteristics, magnetic properties, and microwave frequency performance.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Multidisciplinary
Qasim Raza, Ismat Bibi, Farzana Majid, Shagufta Kamal, Sadia Ata, Aamir Ghafoor, Muhammad I. Arshad, Samiah H. Al-Mijalli, Arif Nazir, Munawar Iqbal
Summary: In this study, SrBixAlxFe12-2xO19 nano-hexaferrites were prepared using a micro-emulsion method, and their ferroelectric, dielectric, magnetic, photocatalytic, and antibacterial properties were investigated. The doped materials showed higher polarization and coercivity values. The optical band gap decreased with increasing doping concentration. The highly doped ferrite exhibited excellent photocatalytic activity and antimicrobial action against textile dyes and bacteria. Therefore, it is a crucial candidate for solar light responsive photocatalytic and antimicrobial applications.
JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
(2023)
Article
Materials Science, Multidisciplinary
Asma Aslam, Atta Ur Rehman, N. Amin, M. Amman, M. Akhtar, N. A. Morley, Merfat S. Al-Sharif, M. M. Hessien, Khaled A. El-Nagdy, Muhammad Imran Arshad
Summary: Tertiary spinel ferrite powders doped with Cd2+ were prepared using a cost-effective sol-gel auto combustion route, and their properties were characterized. The Cd2+ doped ferrite exhibited smaller crystallite size, lower resistivity, smaller AC conductivity, and dielectric loss compared to Mg2+ and Mn2+ doped ferrites. These findings suggest that Cd2+ doped ferrites could be suitable for high-frequency and high-power applications.
MATERIALS CHEMISTRY AND PHYSICS
(2023)
Article
Physics, Condensed Matter
Hadia Noor, Sadia Muniza Faraz, Muhammad Waqas Hanif, Maria Ishaq, Atia Zafar, Saira Riaz, Shahzad Naseem
Summary: Zinc sulfide nanoparticles were incorporated into unsaturated polyester resins (UPR) to form nanocomposites with improved dielectric, magnetic, and mechanical properties. X-ray diffraction confirmed the amorphous nature of the nanocomposites. Scanning electron microscopy images showed good dispersion of ZnS nanoparticles in the UPR matrix. The nanocomposites with 2.5 wt% ZnS concentration exhibited significant or improved values of dielectric constant, ac conductivity, coercivity, magnetic saturation, and magnetic remanence. At a 2 wt% ZnS concentration, the nanocomposites showed good tensile strength and Young's modulus. This study suggests that the semiconducting ZnS nanofillers in the UPR matrix have potential as electromagnetic materials with remarkable properties.
PHYSICA B-CONDENSED MATTER
(2023)
Article
Physics, Condensed Matter
Wakeel Shah, Sadia Muniza Faraz, Zahoorul Hussain Awan
Summary: This study reports the improvement in panchromatic light-harvesting and photovoltaic performance of dye-sensitized solar cells through the adoption of co-sensitization technique by mixing dyes. Natural dyes, Betalain and Anthocyanin, extracted from beetroot and cranberries were used. The dyes were characterized by UV-Vis and FTIR spectroscopy, and solar cells were fabricated and electrically characterized. The solar cell sensitized with mixed dyes showed enhanced performance compared to cells of individual dyes, with a higher short circuit current density, open circuit voltage, and fill factor. The results suggest that mixing dyes from different natural sources can effectively improve the performance of dye-sensitized solar cells.
PHYSICA B-CONDENSED MATTER
(2023)
Article
Materials Science, Ceramics
Muhammad Arshad, Muhammad Azhar Khan, Raqiqa Tur Rasool, Muhammad Imran Arshad, Hind Albalawi, Hisham S. M. Abd-Rabboh, Jolly Jacob, H. M. Noor ul Huda Khan Asghar
Summary: Samples of Sr2Ni2GaxFe12-xO22 (x = 0.00, 0.2, 0.4, 0.6, and 0.8) ceramic were prepared using sol-gel auto combustion route. By substituting Ga3+ at the Fe3+ site, the lattice parameters, density, and electrical and magnetic parameters of the samples were observed to change. These findings suggest the potential applications of these materials in high-frequency devices.
CERAMICS INTERNATIONAL
(2023)
Article
Materials Science, Multidisciplinary
Atta Ur Rehman, Ghulam Abbas, Bilal Ayoub, Nasir Amin, M. Ajaz un Nabi, Nicola A. Morley, Maria Akhtar, Muhammad Imran Arshad, M. Uzair Khalid, M. Afzaal, A. Ghuffar, Muhammad Arshad
Summary: In this study, the sol-gel auto-combustion (SGAC) route was used to prepare Cu0.25Co0.25Mg0.5-xNixCe0.03Fe1.97O4 [NiCCMCF] spinel ferrites. The formation of a single-phase spinel matrix was observed and the crystallite size and specific surface area were characterized. The structural and performance differences of the materials were investigated.
MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS
(2023)
Article
Nutrition & Dietetics
Aslam Khan, Zia Ul-Haq, Sadia Fatima, Jawad Ahmed, Hussah M. Alobaid, Sheraz Fazid, Nawshad Muhammad, Cecilia Garzon, Yasir Ihtesham, Ijaz Habib, Mahamadou Tanimoune, Khalid Iqbal, Muhammad Arshad, Sher Zaman Safi
Summary: Cost-effective interventions are needed to address undernutrition in low- and middle-income countries. A study in Pakistan evaluated the effect of locally produced micronutrient powder supplementation on plasma micronutrient status, hemoglobin level, and growth parameters in children under five. The intervention showed significant improvements in plasma levels of vitamin A, vitamin D, and zinc, as well as hemoglobin level and weight-for-height and weight-for-age z-scores.
Article
Materials Science, Multidisciplinary
Atta Ur Rehman, Sehrish Sharif, H. H. Hegazy, Nicola Morley, Nasir Amin, Maria Akhtar, Muhammad Imran Arshad, Z. Farooq, Z. Munir, T. Munir
Summary: Spinel ferrites with different Co2+ doping levels were synthesized through a sol-gel auto combustion process. The doping of Co2+ led to changes in lattice constant, crystal size, and absorption and vibration bands. The bandgap energy increased with Co2+ doping, and the sample with x = 0.375 showed the highest electrical resistivity and activation energy. This sample also exhibited the maximum dielectric constant and tangent loss, making it suitable for high-frequency resonant circuits applications.
MATERIALS TODAY COMMUNICATIONS
(2023)
Article
Materials Science, Composites
Muhammad Imran Arshad, Kiran Mehmood, Nasir Amin, N. A. Morley, Nguyen Thi Kim Thanh
Summary: This research investigates the impact of graphene nanoplatelets (GNPs) on the properties of CoZnNd ferrites (CZNF), including structure, electrical behavior, magnetic behavior, dielectric properties, and surface morphology. The results demonstrate that the inclusion of GNPs modifies the structural and electromagnetic characteristics of CZNF, with reduced agglomeration observed through SEM images. The composite of CZNF with 2.5 wt % GNPs exhibits excellent magnetodielectric properties, making it suitable for various applications such as high-frequency micro wave shielding, inductors, filters, bolometers, and switching devices.
COMPOSITES COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Muneeba Fatima, Muhammad Sajjad Ul Hasan, Maria Akhtar, Nicola Morley, Nasir Amin, Atta ur Rehman, Muhammad Imran Arshad, Mongi Amami, Bisma Yaqub, Safa Ezzine
Summary: Ce3+ substitution was performed in Cu-Cd spinel nanoferrites, and the structural, morphological, optical, electrical, and dielectric properties were studied. The results showed that the substitution could regulate the properties of nanoferrites and have potential application value in the design of microwave gadgets.
Article
Chemistry, Multidisciplinary
Zarish Nazeer, Ismat Bibi, Farzana Majid, Shagufta Kamal, Muhammad Imran Arshad, Aamir Ghafoor, Norah Alwadai, Abid Ali, Arif Nazir, Munawar Iqbal
Summary: A series of Cd- and Er-doped bismuth ferrites were synthesized using a simple microemulsion technique. The influence of Cd and Er doping on the structural, ferroelectric, photocatalytic, and dielectric properties of bismuth ferrite (BFO) was examined in this research. The prepared materials showed improved saturation polarization and dielectric properties with increased dopant concentration. The photocatalytic activity of the doped materials also increased significantly compared to undoped BiFeO3. Rating: 8/10.
Article
Chemistry, Multidisciplinary
Zartashia Latif, Atta Ur Rehman, Nasir Amin, Muhammad Imran Arshad, Riadh Marzouki
Summary: Nanocomposites of Co0.5Ni0.5Gd0.03Fe1.97O4/graphene nanoplatelets (CNGF/GNPs) were synthesized using a sol-gel auto combustion route. The as-prepared nanocomposites exhibited a cubic structure and a crystallite size of 32.28 nm. The addition of graphene resulted in unique nanoparticles with short stacks of graphene sheets. The composite materials showed high permittivity values at low frequencies.