Article
Chemistry, Physical
Sonachand Adhikari, Olivier Lee Cheong Lem, Felipe Kremer, Kaushal Vora, Frank Brink, Mykhaylo Lysevych, Hark Hoe Tan, Chennupati Jagadish
Summary: The growth of nonpolar m-plane AlGaN on GaN nanowires is limited by the shadowing effect. It is difficult to achieve metal-polar AlGaN nanowires through selective area growth in MOCVD. Nonpolar m-plane GaN nanowires obtained via selective area growth provide an excellent platform for the growth of nonpolar AlGaN MQWs.
Article
Engineering, Electrical & Electronic
Syed Ahmed Al Muyeed, Damir Borovac, Haotian Xue, Xiongliang Wei, Renbo Song, Nelson Tansu, Jonathan J. Wierer
Summary: The study found that adding AlGaN interlayers in high In-content InGaN quantum wells can provide strain balancing and suppress defect formation, resulting in a lower radiative recombination rate. While the non-radiative recombination rates are similar to blue-emitting InGaN quantum wells, the radiative recombination rate is more than an order of magnitude lower compared to lower In-content InGaN quantum wells.
IEEE JOURNAL OF QUANTUM ELECTRONICS
(2021)
Article
Materials Science, Multidisciplinary
Jing Cai, Ruo-He Yao, Yu-Rong Liu, Kui-Wei Geng
Summary: This article proposes a physics-based threshold voltage and drain-source current model based on double-channel AlGaN/GaN HEMTs. The model takes into account the physical properties of the dual-channel HEMT and includes the influence of charges and 2DEGs distributed in lower layers on the upper channel. The accuracy of the proposed model is verified through comparison with simulations and experimental results.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Physics, Applied
Feng Qi Zhao, Zi Zheng Guo, Bo Zhao
Summary: The study investigates the impact of hydrostatic pressure on the binding energy and polaron effect of the bound polaron in a wurtzite AlyGa1-yN/AlxGa1-xN parabolic quantum well, revealing that pressure has a significant effect on the binding energy and polaron effect.
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
(2021)
Article
Physics, Condensed Matter
Y. J. Chai, Y. H. Zan, S. L. Ban
Summary: This study investigates the electron mobility influenced by optical phonons in wurtzite AlxGa1-xN/InyGa1-yN/GaN/AlN heterostructures with InGaN/GaN channels. The results show that the electron mobility is mainly dominated by IF and CO phonon modes in structures with composite channels, leading to higher mobility compared to conventional structures. Optimization of the size and In composition in the composite channel can further enhance the mobility.
SUPERLATTICES AND MICROSTRUCTURES
(2021)
Article
Physics, Applied
Abhiram Gundimeda, Martin Frentrup, Simon M. Fairclough, Menno J. Kappers, David J. Wallis, Rachel A. Oliver
Summary: The influence of AlGaN nucleation layers on zincblende GaN epilayers and the formation of wurtzite phase inclusions in the epilayer were studied. It was found that an increase in aluminum content in the AlGaN nucleation layer leads to an increased presence of wurtzite inclusions. The strong {111}-type faceting observed in the zincblende nucleation layer on an Al0.29Ga0.71N nucleation layer contributes to the formation of wurtzite inclusions at the GaN/ Al0.29Ga0.71N interface.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Crystallography
Masatomo Sumiya, Yuki Takahara, Amira Alghamdi, Yoshiko Nakayama, Fumihiko Uesugi, Yoshitomo Harada, Akira Uedono, Yasutaka Imanaka
Summary: Successful fabrication of AlGaN/GaN and AlGaN/InGaN/GaN heterostructures was achieved, with important implications for controlling the carrier density of two-dimensional electron gas. In the AlGaN/InGaN/GaN system, defined surface morphology and alloy disorder on InGaN, but significantly degraded mobility of 2DEG was observed.
JOURNAL OF CRYSTAL GROWTH
(2021)
Article
Optics
Lei Liu, Feifei Lu, Jian Tian
Summary: The study proposes a heterojunction AlxGa1-xN nanowire array photocathode assisted by an external electric field to enhance electron collection efficiency. The introduction of a built-in electric field by the heterojunction structure and the use of external electric field-assisted methods improve carrier drift and diffusion, leading to increased electron collection efficiency. The GaN-Al0.27Ga0.73N heterojunction nanowires show the best quantum efficiency in the model, and a large-spacing heterojunction Al-component nanowire array with an incident angle of 30 degrees and an external electric field of 2.5V/μm can achieve an overall electron collection ratio of nearly 100%.
JOURNAL OF LUMINESCENCE
(2021)
Article
Physics, Multidisciplinary
Song Li-Na, Lu Yan-Wu
Summary: This study investigates the changes in electronic transport properties caused by InGaN as an AlGaN/GaN insertion layer, and the effects of different factors on the concentration of two-dimensional electron gas (2DEG) in the AlxGa1-xN/InyGa1-yN/GaN double heterojunction. The results indicate that interface roughness scattering and random dipole scattering play important roles in electron transport properties.
ACTA PHYSICA SINICA
(2021)
Article
Computer Science, Information Systems
Yong Huang, Zhiyou Guo, Miao Zhang, Dan Xiang
Summary: This study investigated the impact of different AlxGa1-xN/GaN superlattice electron blocking layer structures on the performance of GaN-based UV LEDs through simulation analysis, revealing that double-peak SL-EBL significantly improves the internal quantum efficiency of the LEDs.
Article
Physics, Applied
Shuhei Ichikawa, Mitsuru Funato, Yoichi Kawakami
Summary: The optical anisotropy of r-plane AlxGa1-xN/AlN quantum wells is investigated, and both theoretical calculations and experimental results confirm the polarization switching at a certain Al composition. The polarization property enables the emitted light to propagate in a specific direction and photopumped lasing is demonstrated on a specific structure of quantum wells.
PHYSICAL REVIEW APPLIED
(2022)
Article
Multidisciplinary Sciences
M. Ajmal Khan, Noritoshi Maeda, Joosun Yun, Masafumi Jo, Yoichi Yamada, Hideki Hirayama
Summary: This research study explores the improvement of efficiency and light output power in AlGaN-based UVB LEDs by optimizing the design and investigating the influence of Ni film. The results provide a new approach for enhancing the performance of high-power UVB LEDs and other optoelectronic devices in III-V semiconductors.
SCIENTIFIC REPORTS
(2022)
Article
Engineering, Electrical & Electronic
M. Nawaz Sharif, M. Ajmal Khan, Qamar Wali, Khalid Ayub, Malika Rani, Fang Wang, Yuhuai Liu
Summary: In the past, low-pressure mercury-based deep-ultraviolet (DUV) lamps were commonly used for real-world applications, but they have drawbacks such as toxicity, heaviness, and high power consumption. This study proposes a smart and clean AlGaN-based DUV light-emitting diode (LED) at 254 nm emission wavelength as an alternative. By incorporating a 5 nm-thin tunnelling assisted Si-doped n-AlGaN layer on the p-side of the LED device, its performance is significantly improved with higher internal quantum efficiency (IQE) and emitted power compared to conventional DUV LED devices. The tunnelling assisted Si-doped AlGaN layer on the p-side of the DUV LED shows promise for disinfection applications in unmanned environments.
OPTICAL AND QUANTUM ELECTRONICS
(2023)
Article
Materials Science, Multidisciplinary
Xiaomeng Fan, Shengrui Xu, Yuzhi Huang, Weiguo Liu, Hongchang Tao, Jincheng Zhang, Yue Hao
Summary: This paper investigates a method of using indium-tin oxide/Au/indium-tin oxide (IAI) structure as transparent conductive layers (TCLs) to improve the current spreading and suppress efficiency droop of UV-LEDs. The morphology and distribution of Au clusters formed by annealing are studied using atomic force microscope and scanning electron microscope. Results show that with the insertion of an Au interlayer, the forward voltage of UV-LED decreases by 5.9% at 20 mA and the light output power and wall plug efficiency increase by 64.2% and 84.2% at 300 mA. Furthermore, the current distribution becomes more uniform and the current spreading characteristics of UV-LED are improved.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2023)
Article
Optics
Shih-Yung Huang, Jian-Cheng Lin, Xiang-Qing Huang, Wei-Kai Wang
Summary: This study focuses on the LED flexible sterilization light source at 280 nm wavelength, and successfully obtained a large-area, flexible deep-ultraviolet light-emitting diode. The sterilization inactivation test with Escherichia coli showed a 95% sterilization rate in 60 seconds, indicating good flexibility and sterilization performance of the sterilization light source.
Article
Chemistry, Physical
Namsoo Lim, Jungwook Min, Jung-Hong Min, Chun Hong Kang, Kuang-Hui Li, Tae -Yong Park, Woochul Kim, Bambar Davaasuren, Tien Khee Ng, Boon S. Ooi, Deok Ha Woo, Ji-Hyeon Park, Yusin Pak
Summary: Orthorhombic kappa-Ga2O3 is a promising ultrawide bandgap material for extreme environment devices. In this study, a kappa-Ga2O3 film was fabricated using metal organic chemical vapor deposition, and its crystallinity was analyzed by X-ray diffraction and transmission electron microscopy. The results demonstrate that this material has excellent ultraviolet-C detection capabilities.
APPLIED SURFACE SCIENCE
(2023)
Article
Engineering, Electrical & Electronic
B. Janjua, Meng Lon Iu, Z. Leger, Z. Yan, Amr S. S. Helmy
Summary: A systematic study of a two sections CPMBRL demonstrates its ability to generate near transform limited pulses with pulse widths of around 130 fs, -3 dB spectral bandwidth of 5.45 nm, and a time-bandwidth product of 0.348. It achieves an average power of 1.5 mW, a repetition rate of 42.4 GHz, and peak power of around 240 mW, enabling a record difference frequency generation conversion efficiency of -38 dB.
IEEE PHOTONICS TECHNOLOGY LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Huafan Zhang, Jung-Hong Min, Tae-Hoon Chung, Kwangjae Lee, Paulraj Gnanasekar, Jung-Wook Min, Tae-Yong Park, Yue Wang, Tien Khee Ng, Udo Schwingenschlogl, Qiaoqiang Gan, Boon S. Ooi
Summary: This study presents a large-area crystalline-semiconductor nitride membrane with a distinct nanoporous surface for efficient and environmentally-friendly organic contaminant degradation in wastewater. The unique nanoporous surface enhances broadband light absorption and provides abundant reactive sites for dye-molecule reaction. The membrane exhibits remarkable dye degradation efficiency (>92%) and total organic carbon removal rate (approximately 50%) under both laboratory and rooftop sunlight test conditions.
Article
Physics, Applied
Xiao Tang, Yi Lu, Rongyu Lin, Che-Hao Liao, Yue Zhao, Kuang-Hui Li, Na Xiao, Haicheng Cao, Wedyan Babatain, Xiaohang Li
Summary: In this research, beta-Ga2O3/NiO heterostructures were directly grown on CeO2 buffered Hastelloy flexible substrates. The CeO2 buffer layer acted as a template for the epitaxial growth of single-oriented NiO and beta-Ga2O3. The resulting photodetectors on Hastelloy substrates exhibited good deformability, mechanical robustness, and high photocurrent under 284 nm light illumination.
APPLIED PHYSICS LETTERS
(2023)
Article
Optics
Sultan Alshaibani, Omar Alkhazragi, Islam Ashry, Chun Hong Kang, Mohammed Sait, Tien Khee Ng, Osman M. Bakr, Boon S. Ooi
Summary: All-inorganic CsPbBr3 nanocrystals are used to extend the field-of-view (FOV) of optical concentrators to 60 degrees, reducing the requirements of pointing, acquisition, and tracking (PAT) in optical wireless communication links. The CsPbBr3 nanocrystals convert transmitted UV light into green light that matches the peak absorption of Si-based detectors, allowing stable communication over the wide FOV.
Article
Nanoscience & Nanotechnology
Noor A. Merdad, Yue Wang, Omar Alkhazragi, Zyad O. F. Mohammed, Partha Maity, Luis Gutierrez-Arzaluz, Haoze Yang, Rounak Naphade, Chun Hong Kang, Tien Khee Ng, Osman M. Bakr, Boon S. Ooi
Summary: In this study, the authors fabricated cesium lead bromide (CsPbBr3) thin films of varying thicknesses and investigated their visible-light communication (VLC) performance. Thicker films were found to have a more homogeneous surface and fewer surface trap states than thinner films. The 20-nm-thick CsPbBr3 film exhibited the best performance with a -3-dB bandwidth of 30.7 MHz and a net data rate of 330 Mb/s, making it suitable for high-power, high-speed, and large-area transmission and detection of visible-light signals.
Article
Nanoscience & Nanotechnology
Shuoyang Qiu, Jiarui Gong, Jie Zhou, Tien Khee Ng, Ranveer Singh, Moheb Sheikhi, Boon S. S. Ooi, Zhenqiang Ma
Summary: Recent demonstrations of grafted p-n junctions combining n-type GaN with p-type semiconductors have shown potential in achieving lattice-mismatch epitaxy-like heterostructures. Ultrathin dielectrics deposited by atomic layer deposition (ALD) serve as a surface passivation and quantum tunneling layer. ZrO2, with excellent properties, can be used as a high-k gate dielectric in GaN-based heterostructures. The interfacial band parameters and band-bending of Ga-polar GaN with ultrathin ALD-ZrO2 were studied, and the bandgap values of ALD-ZrO2 at different thicknesses were investigated.
Article
Materials Science, Multidisciplinary
Amal M. Al-Amri, Tien Khee Ng, Nour El Boukortt, Boon S. Ooi
Summary: In this study, graphene ink was formulated and tested using inkjet printing, and MoS2 ink was deposited as an active layer. The ITO/MoS2/graphene device fabricated showed good rectification behavior and high ON/OFF switching behavior, indicating the potential for low-cost and one-step fabrication of electronics.
Article
Optics
Yue Wang, Jian-Xin Wang, Omar Alkhazragi, Luis Gutierrez-Arzaluz, Huafan Zhang, Chun Hong Kang, Tien Khee Ng, Osman M. Bakr, Omar F. Mohammed, Boon S. Ooi
Summary: Considerable progress has been made in underwater wireless optical communication in complex environments, especially in exploring the deep sea. The color-conversion technique offers a paradigm shift in large-area and omnidirectional light detection, improving data transmission efficiency. This study investigates difluoroboron beta-diketonate fluorophores for their photophysical properties and optical wireless communication performances.
Article
Multidisciplinary Sciences
Yujian Guo, Juan M. Marin, Islam Ashry, Abderrahmen Trichili, Michelle-Nicole Havlik, Tien Khee Ng, Carlos M. Duarte, Boon S. Ooi
Summary: Oceans are vital to human survival, but are being affected by human-made disturbances and noise pollution. This article presents a fiber-based system that aims to reduce noise pollution while providing connectivity to underwater applications. The system enables data monitoring and transfer, as well as continuous power supply for underwater IoT devices.
SCIENTIFIC REPORTS
(2023)
Article
Optics
Omar Alkhazragi, Ming Dong, Liang Chen, Meiwei Kong, Georgian Melinte, Dong Liang, Tien Khee Ng, Junping Zhang, Hakan Bagci, Boon S. Ooi
Summary: The high coherence of lasers can be detrimental in certain applications due to the formation of coherence artifacts. This issue can be resolved by increasing the number of mutually incoherent modes emitted from the laser. Chaotic-cavity VCSELs can achieve broader modulation bandwidths and higher data rates compared to other low-coherence light sources.
Article
Chemistry, Physical
Paulraj Gnanasekar, Karthik Peramaiah, Huafan Zhang, Mathan Kumar Eswaran, Rakesh Rosan Pradhan, Udo Schwingenschlogl, Tien Khee Ng, Qiaoqiang Gan, Jeganathan Kulandaivel, Kuo-Wei Huang, Boon S. Ooi
Summary: In this study, the photoelectrochemical reduction of nitrogen to ammonia was successfully demonstrated using a Mo2C-coated InGaN nanowire electrode. The unique band structure of the Mo2C/GaN/InGaN electrode was found to enhance the production yield and efficiency of ammonia.
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Optics
Shuiqin Zheng, Redha H. Al Ibrahim, Omar Alkhazragi, Tien Khee Ng, Boon S. Ooi
Summary: This paper presents the design, fabrication, and testing of a compact, low-cost, low-crosstalk orbital angular momentum (OAM) sorter based on optical geometric transformation (OGT). The sorter realizes the separation of OAM states using only two phase modulations, achieved by distorting binary gratings through curving the geometrical structure. The fabrication process is simple and the sorter is further improved by incorporating fan-out diffraction, resulting in higher separation and lower cross-talk.
OPTICS AND LASER TECHNOLOGY
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
Juan M. Marin, Islam Ashry, Abderrahmen Trichili, Chun Hong Kang, Omar Alkhazragi, Tien Khee Ng, Boon S. Ooi
Summary: Fiber-optic distributed acoustic sensor (DAS) is used for real-time monitoring of various physical phenomena by detecting backscattered light from a fiber. This study reports on energy harvesting from the DAS pump optical signal to provide power to passive devices. The DAS over a 1.1-km single-mode fiber (SMF) detected a 200-Hz vibration event and harvested a 1.58-mW optical signal to charge a 10-F supercapacitor.
PHOTONIC INSTRUMENTATION ENGINEERING X
(2023)
Article
Chemistry, Physical
Aasif A. Dabbawala, Omer Elmutasim, Mark A. Baker, Georgios Siakavelas, Dalaver H. Anjum, Nikolaos D. Charisiou, Steven J. Hinder, Catherine J. Munro, Marko Gacesa, Maria A. Goula, Kyriaki Polychronopoulou
Summary: In this study, monometallic and bimetallic composite catalysts were synthesized and thoroughly characterized. The results showed that these composites exhibited excellent catalytic performance and stability, achieving good results in hydrodeoxygenation reactions.
APPLIED SURFACE SCIENCE
(2023)
