Article
Optics
Shengjun Zhou, Zhefu Liao, Ke Sun, Ziqi Zhang, Yinzuo Qian, Pengfei Liu, Peng Du, Jingjing Jiang, Zhenxing Lv, Shengli Qi
Summary: This study develops ultrathin tunnel junction (UTJ) deep-UV light-emitting diodes (LEDs) with a low operating voltage of 5.7 V. The formation of Ohmic contact between high-work-function Ni/Au and Mg-Si co-doped n(+)- Al0.45Ga0.55N layer in UTJ is discovered. A high-efficiency sterilization deep-UV light source integrated with 120 UTJ deep-UV LED chips is developed.
LASER & PHOTONICS REVIEWS
(2023)
Article
Optics
Shudan Xiao, Huabin Yu, Hongfeng Jia, Muhammad Hunain Memon, Rui Wang, Haochen Zhang, Haiding Sun
Summary: In this study, an N-polar AlGaN-based deep-ultraviolet light-emitting diode incorporating a tunnel junction as the p-side contact layer was proposed and demonstrated to have improved performance compared to regular N-polar LEDs.
Article
Chemistry, Multidisciplinary
Yong Wang, Zihui Zhang, Long Guo, Yuxuan Chen, Yahui Li, Zhanbin Qi, Jianwei Ben, Xiaojuan Sun, Dabing Li
Summary: This study focused on modeling AlGaN-based deep-ultraviolet (DUV) LEDs with AlGaN as dielectric layers in polarization tunnel junctions (PTJs). It was found that using Al0.7Ga0.3N as the dielectric layer can increase hole concentration and radiative recombination rate in MQWs, but also leads to higher forward voltage requiring greater bias to enhance hole tunneling efficiency in the PTJ. By adopting this approach, enhanced internal quantum efficiency (IQE) and optical output power can be achieved.
Article
Optics
Qifeng Lyu, Huaxing Jiang, Kei May Lau
Summary: The study demonstrates the first integration of monolithically integrated UV LEDs and visible-blind UV PDs on Si substrate, achieving high sensitivity and low dark current. By optimizing the structure and materials, it offers potential for various applications with high-performance UV PDs and LEDs.
Article
Engineering, Electrical & Electronic
Tsung-Yen Liu, Shih-Ming Huang, Mu-Jen Lai, Rui-Sen Liu, Xiong Zhang, Yi-Tsung Chang, Lin-Jun Zhang, Ray-Ming Lin
Summary: This paper presents an AlGaN-based narrow-band ultraviolet-B (NB-UVB) light-emitting diode (LED) with a narrow electroluminescence peak and high external quantum efficiency, but with a decrease in light output power under 60 mA DC aging conditions.
ACS APPLIED ELECTRONIC MATERIALS
(2021)
Article
Chemistry, Analytical
Ruiqiang Xu, Qiushi Kang, Youwei Zhang, Xiaoli Zhang, Zihui Zhang
Summary: AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) have great potential in applications such as sterilization, UV phototherapy, and biological monitoring. Although they have advantages in energy conservation, environmental protection, and easy miniaturization, the efficiency of AlGaN-based DUV LEDs is still low compared to InGaN-based blue LEDs. This paper introduces the research background of DUV LEDs, summarizes various methods to improve the efficiency of DUV LED devices from three aspects: internal quantum efficiency (IQE), light extraction efficiency (LEE), and wall-plug efficiency (WPE). Finally, the future development of efficient AlGaN-based DUV LEDs is proposed.
Review
Crystallography
Kengo Nagata, Taichi Matsubara, Yoshiki Saito, Keita Kataoka, Tetsuo Narita, Kayo Horibuchi, Maki Kushimoto, Shigekazu Tomai, Satoshi Katsumata, Yoshio Honda, Tetsuya Takeuchi, Hiroshi Amano
Summary: A transparent AlGaN homoepitaxial tunnel junction (TJ) was developed as the anode of a deep-UV LED to increase its light output power. The AlGaN TJ LED achieved an operating voltage of 10.8 V and an output power of 57.3 mW, which were among the lowest and highest values, respectively, compared to devices using conventional electrodes. The combination of the AlGaN-based TJ and MgZnO/Al reflective contact showed promise in further improving the light output power.
Article
Physics, Condensed Matter
Saad Rasheed, Muhammad Usman, Shazma Ali, Laraib Mustafa, Hamid Ali
Summary: We have utilized AlInGaN graded layers instead of conventional combination of three p-type layers to improve the performance of UV LEDs. The effects of graded quaternary layers on efficiency droop were investigated. Our proposed structure (LED K2) showed a high peak efficiency of approximately 68% and a significantly reduced efficiency droop of -41% compared to LED K1. The improved efficiency in LED K2 can be attributed to enhanced carrier overlap or recombination in the multiquantum wells.
PHYSICA B-CONDENSED MATTER
(2023)
Article
Optics
Huabin Yu, Zhongjie Ren, Muhammad Hunain Memon, Shi Fang, Danhao Wang, Zhongling Liu, Haochen Zhang, Feng Wu, Jiangnan Dai, Changqing Chen, Haiding Sun
Summary: The TJC-DUV LED designed and reported in this study utilizes tunnel-junction cascading technology to achieve multiple radiative recombinations, doubling the light output power. Compared to conventional DUV LEDs, the wall-plug efficiency of the TJC-DUV LED is boosted by 25% at 60 mA.
CHINESE OPTICS LETTERS
(2021)
Article
Crystallography
Yi-Tsung Chang, Mu-Jen Lai, Rui-Sen Liu, Shu-Chang Wang, Xiong Zhang, Lin-Jun Zhang, Yu-Hsien Lin, Shiang-Fu Huang, Lung-Chien Chen, Ray-Ming Lin
Summary: This study found that the current droop in AlGaN-based UVB light-emitting diodes is more noticeable at higher temperatures, despite both the main and parasitic peaks decreasing in intensity with increasing temperature. However, the slower temperature droop does not occur when the forward current is increased to temperatures above 298 K. After a 6000-hour aging period, the emission wavelengths do not show obvious changes, while the intensity of the parasitic peak remains nearly unchanged. Therefore, the degradation in light output power during long-term operation is not significantly correlated to the presence of the parasitic peak.
Review
Chemistry, Analytical
Muhammad Usman, Shahzeb Malik, Munaza Munsif
Summary: This review discusses the challenges leading to low external quantum efficiency of UV LEDs, along with issues in the growth process such as increased dislocation density. The analysis of light polarization modes and a summary of state-of-the-art external quantum efficiencies, light output power, and peak emission wavelengths in UV-A, UV-B, and UV-C LEDs are also presented.
Article
Physics, Applied
Sibghatullah Khan, Muhammad Usman, Shazma Ali, Saad Rasheed, Sana Saeed
Summary: The radiative recombination rate in yellow light-emitting diodes (LEDs) can be greatly enhanced by converting the last quantum barrier and introducing a graded electron blocking layer, leading to increased carrier concentration and reduced electron-hole asymmetry.
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
(2022)
Article
Materials Science, Multidisciplinary
Sebastian Walde, Cheng-Yao Huang, Chia-Lung Tsai, Wen-Hsuang Hsieh, Yi-Keng Fu, Sylvia Hagedorn, Hung-Wei Yen, Tien-Chang Lu, Markus Weyers, Chia-Yen Huang
Summary: The research successfully prepared high-power and high-quality UVC LED by engineering the lattice constants and dislocation densities of various layers in AlGaN-based UVC LEDs, providing an effective strategy for the preparation of corresponding devices.
Article
Materials Science, Multidisciplinary
Muhammad Usman, Shahzeb Malik, Masroor Hussain, Habibullah Jamal, M. Ajmal Khan
Summary: In this study, the efficiency droop of reference and quaternary-graded final quantum barrier (QGFQB) AlGaN-based UV-C light-emitting diodes was analyzed numerically. The proposed quaternary-graded structure showed a significant reduction in efficiency droop, with improved emission spectrum by over twofold. The simulation results indicate enhanced device performance due to increased carrier concentration and radiative recombination rate.
Article
Engineering, Electrical & Electronic
Liubing Wang, Fujun Xu, Jing Lang, Jiaming Wang, Lisheng Zhang, Xueqi Guo, Chen Ji, Xiangning Kang, Xuelin Yang, Xinqiang Wang, Zhixin Qin, Weikun Ge, Bo Shen
Summary: Thinning the p-AlGaN/p-GaN layer and adopting Ni/Au/Al composite electrodes have been attempted to improve the light extraction efficiency (LEE) of AlGaN-based deep-ultraviolet (DUV) light emitting diodes (LEDs). It is found that the thin p-AlGaN/p-GaN layer reduces light absorption, and the Ni/Au/Al electrodes achieve high reflectivity and Ohmic contact, enhancing light extraction and maintaining fine electrical properties. By using optimized Ni/Au/Al reflective electrodes, the maximum external quantum efficiency of DUV-LEDs is increased by 40% compared to conventional Ni/Au electrodes over the entire current range.
IEEE PHOTONICS JOURNAL
(2023)
Article
Automation & Control Systems
Juntian Qu, Renjie Wang, Peng Pan, Linghao Du, Zetian Mi, Yu Sun, Xinyu Liu
Summary: Nanomaterials possess superior properties and are suitable for various device applications. Nanomanipulation techniques under scanning electron microscopy (SEM) have enabled the testing of mechanical and electrical properties of nanomaterials. However, the seamless integration of mechanical, electrical, and optical testing techniques inside an SEM for multiphysical characterization of nanomaterials is still unexplored. In this work, a nanomanipulation system with integrated micro-photoluminescence setup is reported, and the effect of mechanical compression on the optoelectronic property of nanomaterials is revealed.
IEEE TRANSACTIONS ON AUTOMATION SCIENCE AND ENGINEERING
(2023)
Article
Chemistry, Multidisciplinary
Ayush Pandey, Jungwook Min, Maddaka Reddeppa, Yakshita Malhotra, Yixin Xiao, Yuanpeng Wu, Kai Sun, Zetian Mi
Summary: By developing nanowire excitonic LEDs, the challenge of reduced efficiency in quantum well LEDs at small dimensions can be overcome. A submicron scale green-emitting LED with an external quantum efficiency of 25.2% and a wall-plug efficiency of 20.7% was achieved, the highest values reported for LEDs of this size to our knowledge. Critical factors for achieving excitonic micro-LEDs were identified, including epitaxy of nanostructures for strain relaxation, utilization of semipolar planes to minimize polarization effects, and formation of nanoscale quantum confinement to enhance electron-hole wave function overlap. This work provides a viable path to break the efficiency bottleneck of nanoscale optoelectronics.
Article
Multidisciplinary Sciences
Peng Zhou, Ishtiaque Ahmed Navid, Yongjin Ma, Yixin Xiao, Ping Wang, Zhengwei Ye, Baowen Zhou, Kai Sun, Zetian Mi
Summary: Production of hydrogen fuel from sunlight and water is a promising pathway for carbon neutrality. A strategy using pure water, concentrated solar light, and an indium gallium nitride photocatalyst has achieved a solar-to-hydrogen efficiency of 9.2%. The strategy promotes forward hydrogen-oxygen evolution and inhibits reverse hydrogen-oxygen recombination by operating at an optimal reaction temperature, which can be achieved by harvesting infrared light in sunlight.
Review
Engineering, Electrical & Electronic
Ping Wang, Ding Wang, Shubham Mondal, Mingtao Hu, Jiangnan Liu, Zetian Mi
Summary: III-nitride semiconductors have been extensively studied as promising optoelectronic and electronic materials in the past decades. Recent experimental demonstrations of ferroelectricity in nitride materials have led to significant research interest and expanded their potential in next-generation technologies. Nitride ferroelectric semiconductors, with their unique advantages such as high polarization, breakdown field, Curie temperature, and enhanced optical properties, have enabled a wide range of applications in various devices and systems. This review discusses the development of nitride ferroelectric semiconductors from materials to devices, highlighting their advantages, achievements, challenges, and prospects.
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2023)
Article
Multidisciplinary Sciences
Wan Jae Dong, Yixin Xiao, Ke R. Yang, Zhengwei Ye, Peng Zhou, Ishtiaque Ahmed Navid, Victor S. Batista, Zetian Mi
Summary: This study reports a binary photoelectrode of Pt catalyst-GaN semiconductor with promising efficiency, productivity, and stability for seawater hydrogen evolution. Pt nanoclusters anchored on GaN nanowires were introduced to improve the activity and stability of n(+)-p Si photocathodes for seawater hydrogen evolution. Pt/GaN/Si photocathodes achieved high current density and photon-to-current efficiency in seawater and phosphate-buffered seawater, and also demonstrated a record-high photocurrent density under concentrated solar light.
NATURE COMMUNICATIONS
(2023)
Article
Nanoscience & Nanotechnology
Ping Wang, Ding Wang, Shubham Mondal, Mingtao Hu, Yuanpeng Wu, Tao Ma, Zetian Mi
Summary: Achieving ferroelectricity in III-nitride semiconductors by alloying with rare-earth elements, such as scandium, has opened up possibilities for next-generation electronic, acoustic, photonic, and quantum devices and systems. However, the integration of nitride semiconductors with the complementary metal oxide semiconductor (CMOS) technology has been hindered by the need for sapphire, Si, or SiC substrates. In this study, we demonstrate the growth of single-crystalline ferroelectric nitride semiconductors on CMOS compatible metal-molybdenum, enabling the realization of ferroelectric nitride semiconductors on polycrystalline molybdenum. Robust and wake-up-free ferroelectricity has been measured in the epitaxially grown ScAlN directly on metal, and a ferroelectric GaN/ScAlN heterostructure for synaptic memristor has been proposed and demonstrated, showing potential applications in neuromorphic computing.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Ding Wang, Ping Wang, Shubham Mondal, Mingtao Hu, Yuanpeng Wu, Tao Ma, Zetian Mi
Summary: Computing in the analog regime using nonlinear ferroelectric resistive memory arrays can potentially alleviate the energy constraints and complexity/footprint challenges imposed by digital von Neumann systems. In this study, ferroelectric and analog resistive switching in an epitaxial nitride heterojunction comprised of ultrathin nitride ferroelectrics, specifically ScAlN, has been demonstrated. The results show high ON/OFF ratios, uniformity, retention, and cycling endurance, along with the capability for multistate operation and image processing.
ADVANCED MATERIALS
(2023)
Article
Physics, Applied
Yuanpeng Wu, Ping Wang, Woncheol Lee, Anthony Aiello, Parag Deotare, Theodore Norris, Pallab Bhattacharya, Mackillo Kira, Emmanouil Kioupakis, Zetian Mi
Summary: Both 2D TMDs and III-V semiconductors are potential platforms for quantum technology, but each with its limitations. 2D TMDs have a large exciton binding energy and customizable quantum properties, but compatibility issues with existing industrial processes. On the other hand, III-nitrides have been widely used in light-emitting devices and power electronics but lack exploitation of excitonic quantum aspects. Recent advancements in 2D III-nitrides have shown promise in achieving room-temperature quantum technologies.
APPLIED PHYSICS LETTERS
(2023)
Editorial Material
Materials Science, Multidisciplinary
Grace Xing, Zetian Mi, Srabanti Chowdhury
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Nanoscience & Nanotechnology
Jiarui Gong, Jie Zhou, Ping Wang, Tae-Hyeon Kim, Kuangye Lu, Seunghwan Min, Ranveer Singh, Moheb Sheikhi, Haris Naeem Abbasi, Daniel Vincent, Ding Wang, Neil Campbell, Timothy Grotjohn, Mark Rzchowski, Jeehwan Kim, Edward T. Yu, Zetian Mi, Zhenqiang Ma
Summary: This study successfully demonstrates the creation, transfer-printing, and characteristics of high-quality single-crystalline aluminum nitride nanomembranes (AlN NMs). The crystalline quality of the NMs remains intact after transfer, and partial relaxation of tensile stress is observed. Additionally, piezoelectricity at the nanoscale is confirmed. This research provides a novel approach for the development of AlN-based heterogeneous integration and future nanoelectronics and optoelectronics.
ADVANCED ELECTRONIC MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
David Arto Laleyan, Woncheol Lee, Ying Zhao, Yuanpeng Wu, Ping Wang, Jun Song, Emmanouil Kioupakis, Zetian Mi
Summary: Two-dimensional hexagonal boron nitride (h-BN) shows great promise for far ultraviolet (UV-C) light emission with higher quantum efficiency than other indirect bandgap materials, enabled by strong excitonic effects and efficient exciton-phonon interactions. This study offers a new approach for the design and development of far UV-C optoelectronic devices and quantum photonic devices using 2D semiconductor active regions.
Article
Chemistry, Physical
Danhao Wang, Ding Wang, Peng Zhou, Mingtao Hu, Jiangnan Liu, Shubham Mondal, Tao Ma, Ping Wang, Zetian Mi
Summary: Through high-resolution X-ray photoelectron spectroscopy measurements, we discovered a thick oxide layer on ScAlN when exposed to air, which significantly affects its characterization and electronic structure evaluation. By excluding the possible impact from the surface oxide layer, the band alignment of Sc0.18Al0.82N/GaN can be accurately determined. Simulation results further demonstrate that the Sc0.18Al0.82N barrier layer offers excellent charge carrier confinement and a high density of two-dimensional electron gas (2DEG) at the heterostructure interface, crucial for high-performance GaN-based high electron mobility transistors (HEMTs).
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Physical
Danhao Wang, Shubham Mondal, Pat Kezer, Mingtao Hu, Jiangnan Liu, Yuanpeng Wu, Peng Zhou, Tao Ma, Ping Wang, Ding Wang, John T. Heron, Zetian Mi
Summary: Incorporating scandium (Sc) into III-nitride lattice offers remarkable ferroelectric and optical properties. Yttrium (Y), a substitute for Sc, shows potential in alloyed III-nitride materials. In this study, we investigated the energy band gap alignment and transport properties of a YAlN-based HEMT structure. Experimental results showed promising electrical characteristics and compatibility with semiconductor technology, making it a significant development in next-generation HEMTs.
APPLIED SURFACE SCIENCE
(2023)
Article
Engineering, Electrical & Electronic
Suhyun Nam, Wenhao Peng, Ping Wang, Ding Wang, Zetian Mi, Amir Mortazawi
Summary: Modern wireless communication systems are becoming more complex and pose new challenges for RF front-end design. This study introduces a film bulk acoustic wave resonator (FBAR) with a composite ferroelectric/piezoelectric transduction layer that can operate selectively at higher order resonant modes in the millimeter wave spectrum without compromising k(t)(2). The resonator has a fundamental mode at GHz with k(t)(2) of 5.2%, but can switch to a higher order response at 31 GHz with k(t)(2) of 5.5%).
IEEE MICROWAVE AND WIRELESS TECHNOLOGY LETTERS
(2023)
Review
Chemistry, Physical
Wan Jae Dong, Zetian Mi
Summary: The depletion of carbon-based fuels and emerging environmental problems are driving the demand for green energy sources. This review introduces 1D nanostructured III-nitrides for artificial photosynthesis, highlighting their synthesis methods, properties, efficiency, and stability. The challenges and prospective insights for future development are also discussed.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)