Article
Physics, Applied
Ping Wang, Ding Wang, Nguyen M. Vu, Tony Chiang, John T. Heron, Zetian Mi
Summary: Ferroelectricity has been successfully demonstrated in ScxAl1-xN epitaxial films grown on GaN templates by molecular beam epitaxy, showing distinct polarization switching and excellent properties, such as a high coercive field and long polarization retention time. This achievement opens up possibilities for integrating high-performance ferroelectric functionality into established semiconductor platforms for various electronic and photonic device applications.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Ping Wang, Ding Wang, Shubham Mondal, Zetian Mi
Summary: In this study, robust ferroelectricity was demonstrated in single-crystalline thin films. The crystallographic alignment was confirmed using x-ray diffraction measurements. The highly uniform coercive field and remnant polarization were observed in the nearly lattice-matched heterostructure. The reliability of the ferroelectricity was systematically characterized and showed negligible degradation after a large number of switching cycles. This research provides a feasible pathway for fully epitaxial integration of ferroelectricity into nitride heterostructures, with important applications in various fields.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Ding Wang, Shubham Mondal, Jiangnan Liu, Mingtao Hu, Ping Wang, Samuel Yang, Danhao Wang, Yixin Xiao, Yuanpeng Wu, Tao Ma, Zetian Mi
Summary: We demonstrate ferroelectric switching in yttrium-doped nitride semiconductors. Yttrium 0.07Al0.93N films were grown on GaN/sapphire templates and exhibited a coercive field of 6 MV/cm and a switchable polarization of 130 mu C/cm(2). Ferroelectric switching was confirmed through capacitance-voltage loops and polarity-sensitive wet etching. This study expands the family of nitride ferroelectrics and opens up possibilities for applications in III-nitride based devices.
APPLIED PHYSICS LETTERS
(2023)
Article
Optics
Qi Lin, Jie Huang, Liying Lin, Wei Luo, Wen Gu, Kei May Lau
Summary: This article reports on the continuous wave lasing of 980nm electrically pumped quantum well lasers directly grown on silicon, and compares them with lasers grown on other substrates. The results show that although lasers grown on silicon have slightly higher threshold current, it still demonstrates a promising step towards realizing quantum well lasers on silicon.
Article
Physics, Applied
Eric N. Jin, Andrew C. Lang, Brian P. Downey, Vikrant J. Gokhale, Matthew T. Hardy, Neeraj Nepal, D. Scott Katzer, Virginia D. Wheeler
Summary: This work demonstrates the growth of SrTiO3 thin films on high-electron-mobility transistor heterostructures based on an emergent ultra-wide bandgap (UWBG) semiconductor ScAlN, and investigates the effects of pre-growth chemical treatments on the heterostructure properties. It is found that among the treatments studied, the solvent and sulfuric-phosphoric acid cleans have the least disruptive effects on the electrical properties of the GaN channel, while the sulfuric-phosphoric acid clean results in the best oxide crystallinity. The transmission electron microscopy imaging reveals that intermixing occurs at the oxide-nitride interfaces for both samples, but the sample treated with sulfuric-phosphoric acid has lower interface roughness and larger STO grain size.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Rahmat Hadi Saputro, Ryo Matsumura, Naoki Fukata
Summary: This study reveals the mechanism of dopant redistribution in Sb-doped Ge epitaxial films grown by molecular beam epitaxy, providing insights into the behavior of substituted Sb atoms in forming n-type Ge films. The understanding of these processes opens up possibilities for achieving n(+)-Ge thin films for Ge-based devices with improved electrical properties.
CRYSTAL GROWTH & DESIGN
(2021)
Article
Chemistry, Physical
Mansi Agrawal, Anubha Jain, Vishakha Kaushik, Akhilesh Pandey, B. R. Mehta, R. Muralidharan
Summary: In this study, catalyst-free GaN nanowires were grown on Si (111) substrates by plasma-assisted molecular beam epitaxy, followed by the deposition of a few layers of MoS2 by chemical vapor deposition. The morphology and vibrational properties of the MoS2/GaN nanowires on Si (111) substrates were analyzed using scanning electron microscopy and Raman spectroscopy. The results indicate the potential of MoS2/GaN nanowires heterojunction for future optoelectronic devices due to their exceptional structural and vibrational properties.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Multidisciplinary
Mario F. Zscherp, Nils Mengel, Detlev M. Hofmann, Vitalii Lider, Badrosadat Ojaghi Dogahe, Celina Becker, Andreas Beyer, Kerstin Volz, Joerg Schoermann, Sangam Chatterjee
Summary: This study successfully optimized the quality of c-GaN epitaxial layers by introducing pre-growth treatments and buffer layers, achieving nearly perfect crystallinity and smooth surfaces and interfaces. The optimized growth parameters resulted in extremely small surface roughness and very limited stacking fault densities in phase pure c-GaN layers. The high structural quality of the epitaxial layers was further confirmed through photoluminescence spectroscopy.
CRYSTAL GROWTH & DESIGN
(2022)
Article
Engineering, Electrical & Electronic
A. Belio-Manzano, L. I. Espinosa-Vega, I. E. Cortes-Mestizo, C. A. Mercado-Ornelas, F. E. Perea-Parrales, S. Gallardo-Hernandez, V. D. Compean-Garcia, J. L. Regalado-de la Rosa, E. Castro-Camus, A. Yu Gorbatchev, Victor H. Mendez-Garcia
Summary: This paper analyzes the molecular beam epitaxial growth and physical properties of InGaAs alloy layers on GaAs (100) substrates with varying In concentration. Hyperbolic-tangent compositional gradients are observed and the occurrence of dislocations in these gradients is explored.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2022)
Article
Materials Science, Coatings & Films
Raghad S. H. Saqat, Andrew W. Forbes, Niraj Bhattarai, Ian L. Pegg, John Philip
Summary: Ferromagnetic (Fe70Ni30)(96)Mo-4 thin films were grown using molecular beam epitaxy, and their magnetic properties and magnetocaloric effects were investigated. X-ray diffraction and vibrating sample magnetometry measurements confirmed the crystalline ferromagnetic (Fe70Ni30)(96)Mo-4 phase with a Curie point near room temperature. To assess the suitability of this material for magnetocaloric applications, a large magnetic entropy change with a wide temperature span and high relative cooling power near the Curie temperature comparable to rare-earth-based materials operating near room temperature were observed.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Chemistry, Multidisciplinary
Vladimir G. Dubrovskii, Simon Escobar Steinvall, Virginie de Mestral, Rajrupa Paul, Jean-Baptiste Leran, Mahdi Zamani, Elias Z. Stutz, Anna Fontcuberta Morral
Summary: Selective area growth of Zn3P2 on InP provides high-quality semiconductor nanostructures made of earth-abundant elements. In the precoalescence stage, Zn3P2 emerges in the form of nanoislands and undergoes a shape transformation. The results are presented in dimensionless variables, allowing simultaneous understanding of islands grown in differently sized pinholes and for different growth times.
CRYSTAL GROWTH & DESIGN
(2021)
Article
Nanoscience & Nanotechnology
Kenny Huynh, Michael E. Liao, Akhil Mauze, Takeki Itoh, Xingxu Yan, James S. Speck, Xiaoqing Pan, Mark S. Goorsky
Summary: The orientational dependence of interfacial reaction between aluminum and different β-Ga2O3 substrates (010, (001), and ((2) over bar 01)) was investigated. It was found that the orientation of β-Ga2O3 substrates influences the formation of aluminum oxide layers and diffusional pathways.
Article
Materials Science, Coatings & Films
Theresa P. Ginley, Stephanie Law
Summary: Traditionally, layered van der Waals (vdW) materials grown by physical vapor deposition techniques are thought to have weak interactions with the substrate, resulting in films with triangular domains and a terraced morphology. However, research demonstrates that a prototypical vdW material, Bi2Se3, will form a nanocolumn morphology when grown on GaAs(001) substrates, due to a relatively strong film/substrate interaction, long adatom diffusion lengths, and a high reactive selenium flux. This discovery opens the possibility of growing self-assembled vdW structures even in the absence of strain.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2021)
Article
Physics, Applied
Shek-Ying Lin, Zhihao He, Yick On To, Iam Keong Sou
Summary: Nowadays, children and teenagers are increasingly exposed to blue and ultraviolet light due to their frequent use of electronic display devices and participation in disco parties and concerts with UV light. We have developed a Fe:Pd/ZnSe photodetector with excellent rejection power for green and red light. This compact and efficient detector can accurately measure the blue and UV content of different LED light bulbs, providing awareness of vision damaging radiation.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Nemanja Peric, Corentin Durand, Maxime Berthe, Yan Lu, Kekeli N'Konou, Roland Coratger, Isabelle Lefebvre, Philipp Ebert, Louis Biadala, Ludovic Desplanque, Xavier Wallart, B. Grandidier
Summary: The knowledge of band alignment in semiconductor heterostructures is important for device performance. In this study, the direction of current flow in In0.53Ga0.47As/InP heterostructure nanowires was controlled, and the band offsets at the buried heterointerface were directly measured using low temperature multiple-probe tunneling spectroscopy. The results indicate the formation of an interface with a quality comparable to two-dimensional In0.53Ga0.47As/InP heterostructures.
APPLIED PHYSICS LETTERS
(2022)
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.
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
Ding Wang, Ping Wang, Minming He, Jiangnan Liu, Shubham Mondal, Mingtao Hu, Danhao Wang, Yuanpeng Wu, Tao Ma, Zetian Mi
Summary: In this Letter, fully epitaxial ScAlN/AlGaN/GaN based ferroelectric high electron mobility transistors (HEMTs) were demonstrated using molecular beam epitaxy. The fabricated ferroelectric gate HEMTs showed counterclockwise hysteretic transfer curves with a wide threshold voltage tuning range, a large ON/OFF ratio, and reconfigurable output characteristics. The high quality ferroelectric gate stack and effective ferroelectric polarization coupling lead to improved subthreshold performance. These results provide fundamental insight into the ferroelectric polarization coupling and threshold tuning processes in ferroelectric nitride heterostructures and have promising applications in next-generation electronics.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Fengyan Yang, Guangcanlan Yang, Ding Wang, Ping Wang, Juanjuan Lu, Zetian Mi, Hong X. Tang
Summary: In this study, high-fidelity ferroelectric domain switching and periodic poling of Al-polar ScAlN thin film was demonstrated, which was epitaxially grown on a c-axis sapphire substrate using gallium nitride as a buffer layer. This advancement in controlling the polarization of epitaxial ScAlN presents great potential for its application in ferroelectric storage and nonlinear optics.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Ding Wang, Shubham Mondal, Jiangnan Liu, Mingtao Hu, Ping Wang, Samuel Yang, Danhao Wang, Yixin Xiao, Yuanpeng Wu, Tao Ma, Zetian Mi
Summary: We demonstrate ferroelectric switching in yttrium-doped nitride semiconductors. Yttrium 0.07Al0.93N films were grown on GaN/sapphire templates and exhibited a coercive field of 6 MV/cm and a switchable polarization of 130 mu C/cm(2). Ferroelectric switching was confirmed through capacitance-voltage loops and polarity-sensitive wet etching. This study expands the family of nitride ferroelectrics and opens up possibilities for applications in III-nitride based devices.
APPLIED PHYSICS LETTERS
(2023)
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)