Article
Materials Science, Multidisciplinary
Vishnu Aggarwal, Sudhanshu Gautam, Aditya Yadav, Rahul Kumar, Bipul Kumar Pradhan, Brajesh S. Yadav, Govind Gupta, Senthil Kumar Muthusamy, Sumeet Walia, Sunil Singh Kushvaha
Summary: Recently, there has been a great demand for highly responsive photodetectors that can detect a wide range of wavelengths. Researchers have successfully fabricated a broadband metal-semiconductor-metal photodetector by integrating sputtered Bi2Se3 with laser molecular beam epitaxy grown GaN film. This photodetector shows high responsivity in both the ultraviolet and near-infrared regions.
MATERIALS RESEARCH BULLETIN
(2024)
Article
Multidisciplinary Sciences
Danish Shamoon, Kishor Upadhyaya, Sonnada M. Shivaprasad
Summary: Scaling down the size of semiconductor cavity lasers and engineering their electromagnetic environment in the Purcell regime can lead to significant advancements in nanodevices fabrication. An unprecedented observation of coherent Cathodoluminescence from GaN nanocavities has been reported, with the potential for fabrication of very high density cavity lasers that are addressable by simple deflection and tuning of incident electron beams.
SCIENTIFIC REPORTS
(2021)
Article
Optics
Chanhyung Park, Jeongmin Shin, Sanmun Kim, Songju Lee, Juho Park, Jaehyeok Park, Sehong Park, Seunghyup Yoo, Min Seok Jang
Summary: Researchers propose a new simulation method, called the diffraction matrix method (DMM), that accurately predicts the optical characteristics of periodically corrugated OLEDs with significantly faster calculation speed. The method decomposes the light emitted by a dipolar emitter into plane waves and tracks the diffraction behavior using diffraction matrices. The calculated optical parameters show quantitative agreement with those predicted by the finite-difference time-domain (FDTD) method. Furthermore, the method evaluates the wavevector-dependent power dissipation of a dipole and identifies the loss channels inside OLEDs in a quantitative manner.
Article
Engineering, Electrical & Electronic
Ramit Kumar Mondal, Vipul Pandey, Vijay Chatterjee, Suchandan Pal
Summary: The polarization-dependent light extraction efficiency (LEE) of AlGaN flip-chip deep ultraviolet light emitting diodes with embedded periodic photonic structure (PPS), surface PPS, and double-sided PPS configurations was studied using the 3D FDTD method. Among the configurations, the double-sided PPS showed the greatest improvement in LEE, followed by the embedded PPS configuration. The surface PPS offered the least improvement in LEE compared to the conventional deep-UV LED structure. The improvements in TE, TM, and overall LEE were found to be approximately 128.37%, 59.18%, and 99% for the double-sided PPS configuration compared to the conventional deep-UV LED.
OPTICAL AND QUANTUM ELECTRONICS
(2021)
Article
Optics
Qifa Liu, Zhenhai Wang, Lihui Zhu, Xiefeng Cheng, Jin Wang
Summary: The method of using nano-grooves to improve GaN-LED light extraction efficiency was studied, and its effectiveness was experimentally verified.
OPTICS AND LASER TECHNOLOGY
(2021)
Article
Engineering, Electrical & Electronic
Shaoliang Yang, Dongming Zhou, Jinde Cao, Yanbu Guo
Summary: We propose a Vision Transformer-based Generative Adversarial Network (Transformer-GAN) for enhancing low-light images. Our method consists of feature extraction and image reconstruction subnets, and introduces multi-head multi-covariance self-attention and Light feature-forward module structures. Experiments show that our method outperforms existing methods on low-light datasets.
IEEE SIGNAL PROCESSING LETTERS
(2022)
Article
Optics
Weidong Wang, Chunshuang Chu, Jiamang Che, Sheng Hang, Hua Shao, Kangkai Tian, Yonghui Zhang, Zi-Hui Zhang
Summary: The study shows that the use of a thin p-GaN layer can enhance the light extraction efficiency (LEE) and external quantum efficiency (EQE) of AlGaN-based DUV LEDs. However, it may also lead to current crowding effect and reduced internal quantum efficiency (IQE), thereby restricting further improvement of EQE.
Article
Physics, Applied
Kazuki Nomoto, Huili Grace Xing, Debdeep Jena, YongJin Cho
Summary: High-quality N-polar GaN p-n diodes were successfully fabricated on single-crystal N-polar GaN bulk substrates using plasma-assisted molecular beam epitaxy. These diodes exhibit high on/off current ratio and ideality factor at room temperature, and their performance remains relatively stable at elevated temperatures.
APPLIED PHYSICS EXPRESS
(2022)
Article
Chemistry, Physical
Sihao Xia, Yu Diao, Caixia Kan
Summary: The study demonstrates that the nanostructure photoemitter based on parallel aligned (Al)GaN nanowall arrays shows higher photoelectric conversion efficiency, but is also affected by negative impacts on quantum efficiency and emitted photocurrent.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Energy & Fuels
Ali Elrashidi, Enrico Traversa, Basma Elzein
Summary: This article presents a highly sensitive ultra-thin optical sensor for carbon dioxide detection using plasmonic nanoparticles distributed uniformly on a nanowall honeycomb structure. The sensor shows excellent performance in the visible and near-infrared regions, with high intensity sensitivity and refractive index sensitivity. This innovative sensor has great potential for gas detection applications.
FRONTIERS IN ENERGY RESEARCH
(2022)
Article
Materials Science, Multidisciplinary
Monika Rolinska, Fredrik Gustavsson, Peter Hedstrom
Summary: The extraction replica technique is a useful method for preparing transmission electron microscopy samples, which eliminates the influence of the surrounding matrix on compositional or crystallographic analysis. This study summarizes the techniques for extracting various precipitates from different alloys and compares the efficiency of the direct replica method with the two-stage replica method. The results indicate that the direct method has a higher particle extraction efficiency for smaller particles and also facilitates the analysis of other features in certain cases.
MATERIALS CHARACTERIZATION
(2022)
Article
Optics
Sheng Hang, Gai Zhang, Chunshuang Chu, Yonghui Zhang, Quan Zheng, Qing Li, Zi-Hui Zhang
Summary: This report systematically investigates the impact of different mesa designs on the optical and electrical characteristics of GaN-based micro-LEDs. The results show that using beveled mesas can enhance light extraction efficiency, but it also increases charge-coupling effect and nonradiative recombination.
Article
Nanoscience & Nanotechnology
Jumpei Yamada, Ai Mizuno, Tatsuya Honda, Keigo Yoshida, Rie Togashi, Ichirou Nomura, Tomohiro Yamaguchi, Tohru Honda, Katsumi Kishino
Summary: This study investigated the growth behavior of Indium gallium nitride (InGaN)-based nanocolumn arrays and fabricated red emission nanocolumn micro-light emitting diodes (μ-LEDs). The internal structure of the InGaN/GaN superlattice (SL) layer under the multiple-quantum-well (MQW) active layers was evaluated using scanning transmission electron microscopy (STEM) analysis. It was found that the crystal plane at the top of the nanocolumn changed as the number of SL pairs increased, and the growth of the semipolar (10-11) plane InGaN active layers was observed. Red nanocolumn μ-LEDs with an φ12μm emission window were fabricated, achieving an external quantum efficiency of 1.01% at 51 A cm(-2).
Article
Physics, Applied
Amandeep Kaur, Kousik Bera, Santosh Kumar Yadav, S. M. Shivaprasad, Anushree Roy, Subhabrata Dhar
Summary: Recently, it has been found that the electron mobility in wedge-shaped c-GaN nanowall networks has exceeded the theoretical mobility limit for bulk GaN. Additionally, a significant blue-shift of the bandgap has been observed. These findings can be explained by the formation of a two-dimensional electron gas (2DEG) at the central vertical plane of the walls, which is caused by polarization charges on the inclined faces. Strain was also examined, but it was found to have no effect on the bandgap enhancement.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Gunjan Yadav, Reema Gupta, Anjali Sharma, Monika Tomar
Summary: This study presents the growth and optimization of GaN thin films with preferred c-axis (0002) orientation on Si (111) substrate using Laser Molecular Beam Epitaxy technique. The nitrogen gas flow during film deposition was optimized to enhance the optical efficiency of the GaN thin films. The structural, morphological, and optical properties of the films were analyzed using XRD, AFM, PL, and FTIR spectroscopy. The refractive index of the films decreased with the increase in deposition gas flow, and the refractive index dispersion was analyzed using the SPR technique.
Article
Physics, Applied
D. Shamoon, J. Dermol-Cerne, L. Rems, M. Rebersek, T. Kotnik, S. Lasquellec, C. Brosseau, D. Miklavcic
APPLIED PHYSICS LETTERS
(2019)
Article
Physics, Applied
D. Shamoon, S. Lasquellec, C. Brosseau
APPLIED PHYSICS LETTERS
(2019)
Article
Materials Science, Multidisciplinary
Rajendra Kumar, Sanjay Nayak, S. M. Shivaprasad
MATERIALS RESEARCH EXPRESS
(2019)
Article
Physics, Applied
Sanjay Nayak, Shashidhara Acharya, Madhusmita Baral, Magnus Garbrecht, Tapas Ganguli, S. M. Shivaprasad, Bivas Saha
APPLIED PHYSICS LETTERS
(2019)
Article
Chemistry, Physical
Sanjay Nayak, K. K. Nagaraja
JOURNAL OF ALLOYS AND COMPOUNDS
(2020)
Article
Chemistry, Physical
Sanjay Nayak, Satadeep Bhattacharjee, Jung-Hae Choi, Seung Cheol Lee
JOURNAL OF PHYSICAL CHEMISTRY A
(2020)
Article
Chemistry, Physical
B. Archana, Nagaraju Kottam, Sanjay Nayak, K. B. Chandrasekhar, M. B. Sreedhara
JOURNAL OF PHYSICAL CHEMISTRY C
(2020)
Article
Materials Science, Coatings & Films
Bidesh Biswas, Sanjay Nayak, Vijay Bhatia, Ashalatha Indiradevi Kamalasanan Pillai, Magnus Garbrecht, Mohammed H. Modi, Mukul Gupta, Bivas Saha
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2020)
Article
Materials Science, Coatings & Films
Sanjay Nayak, Mit H. Naik, Manish Jain, Umesh Waghmare, Sonnada M. Shivaprasad
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2020)
Article
Physics, Applied
Rajendra Kumar, Sanjay Nayak, Magnus Garbrecht, Vijay Bhatia, Ashalatha Indiradevi Kamalasanan Pillai, Mukul Gupta, S. M. Shivaprasad, Bivas Saha
Summary: This article investigates the formation of oxygen defects in metallic TiN and semiconducting rock salt-(Al,Sc)N using first-principles density functional theory, synchrotron-based x-ray absorption spectroscopy (XAS) analysis, and scanning transmission electron microscopy-energy-dispersive x-ray spectroscopy mapping. The modeling results reveal that oxygen in TiN and rock salt-(Al,Sc)N prefers to be in the defect complex of substitutional and interstitial oxygen types, with the distribution influenced by the oxygen partial pressure.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Condensed Matter
Shailesh Kalal, Sanjay Nayak, Akhil Tayal, Jens Birch, Rajeev Rawat, Mukul Gupta
Summary: The study reveals that structural disorder in δ-NbN thin films leads to a lower superconducting transition temperature than the theoretically predicted value. Experiments and theoretical analysis show that under N-rich growth conditions, atomic and molecular N-interstitial defects assisted by cation vacancies form spontaneously, resulting in electronic structure smearing around the Fermi level.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2021)
Article
Multidisciplinary Sciences
Danish Shamoon, Kishor Upadhyaya, Sonnada M. Shivaprasad
Summary: Scaling down the size of semiconductor cavity lasers and engineering their electromagnetic environment in the Purcell regime can lead to significant advancements in nanodevices fabrication. An unprecedented observation of coherent Cathodoluminescence from GaN nanocavities has been reported, with the potential for fabrication of very high density cavity lasers that are addressable by simple deflection and tuning of incident electron beams.
SCIENTIFIC REPORTS
(2021)
Article
Chemistry, Multidisciplinary
Archana K. Munirathnappa, Chethana Aranthady, Ananda Kulal, Sachin Kumar Maurya, Kaushal Kumar, Sanjay Nayak, Seung Cheol Lee, Nalini G. Sundaram
Summary: In this study, we reported the synthesis, crystal structure, and upconversion emission of NaLa(WO4)(2): Yb3+/Er3+ in both bulk and nanomaterial forms. The host lattice dynamics of the disordered NaLa(WO4)(2) matrix were investigated using DFT and neutron diffraction studies, revealing the presence of phonons at a cut-off frequency of approximately 912 cm(-1). The optimized concentration of NaLa0.865Er0.035Yb0.1(WO4)(2), referred to as UCB and UCN, was obtained using a solvothermal method. High-resolution microscopy studies showed the existence of high-density edge dislocations in UCN nanomaterials, leading to enhanced phonon scattering. Both UCB and UCN materials exhibited intense pump power-dependent upconversion green emission under 980 nm laser irradiation. Furthermore, we demonstrated the non-toxicity of UCB and UCN towards bacterial and fungal strains, as well as their potential application in in vitro cell imaging. Overall, the neutron diffraction, DFT, microscopy, and spectroscopic analysis provided valuable insights into the structure-property relationship of these biocompatible upconversion green fluorescent bifunctional NaLa(WO4)(2) materials.
Article
Materials Science, Multidisciplinary
Sanjay Nayak, Chandan K. Singh, Martin Dahlqvist, Johanna Rosen, Per Eklund, Jens Birch
Summary: Recent experiments have shown that bulk superconductivity can be induced in AlB2-type ZrB2 and HfB2 by vanadium (V) doping. In this study, first-principles calculations were used to investigate the origin of superconductivity in V-doped ZrB2. The results suggest that doping-induced stress weakens the electron-phonon coupling (EPC), but concurrently induced charges strengthen it. However, the calculated critical transition temperature is at least one order of magnitude lower than experimental results, indicating a complex origin of superconductivity in these materials.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Sanjay Nayak, Madhusmita Baral, Mukul Gupta, Jaspreet Singh, Magnus Garbrecht, Tapas Ganguli, S. M. Shivaprasad, Bivas Saha
