bluuebunny/crossref_metadata_2025_split huggingface dataset:
Epitaxial Growth and Doping of N-Polar AlN by Plasma-Assisted Molecular Beam Epitaxy
Authors: Ahmadi Elaheh , Khan Irfan 
Published: August 2024

In recent years, AlN has garnered significant attention in the research community due to its excellent electronic properties. AlN, which is an ultra-wide bandgap material with a direct band gap of 6.2 eV, has a high breakdown electric field (12 MV/cm) and high thermal conductivity. In addition, band engineering can be achieved by alloying AlN with Gallium (Ga), Indium (In), and Scandium (Sc), and two-dimensional electron gas (2DEG) is formed at the AlGaN/AlN interface due to strong piezoelectric and spontaneous polarization. Furthermore, AlN has high-temperature stability, which is suitable for application in harsh environments. Due to these unique properties, AlN has gained attention as a promising candidate for the next generation of high power electronic and optoelectronic applications.
In this talk, we present the demonstration of controllable Si doping in N-polar AlN films grown on single crystal AlN substrates by plasma assisted molecular beam epitaxy (PAMBE). Through optimization of growth conditions, we obtained high quality N-polar AlN films at high temperatures. However, our studies revealed that Si incorporation dramatically decreases at such high growth temperature. To enable higher Si incorporation, a hybrid growth scheme was developed, using a combination of low-temperature and high-temperature growth condition and by using Ga as a surfactant at low growth temperature. By lowering the growth temperature of AlN to 750°C, we were able to incorporate Si with concentrations as high as 2x1020 cm-3 and demonstrated an electron concentration as high as 1.25x1019 cm-3 at room temperature.
(Invited) Functional Complex Oxides for Next-Generation Logic, Memory, Sensing, and Beyond
Authors: Martin Lane W. 
Published: August 2024

Complex-oxide materials possess a range of interesting properties and phenomena that make them candidates for next-generation devices and applications. But before these materials can be integrated into state-of-the-art devices, it is important to understand how to control and engineer their response in a deterministic manner. In this talk, we will discuss some of the state-of-the-art science, engineering, and utilization of complex ferroic materials and their potential for emergent order and phenomena that can enable new device function. We will explore the role of the epitaxial thin-film growth process and the use of epitaxial constraints to engineer a range of systems with special attention to ferroelectric (i.e., materials with robust spontaneous polarization that can be switched with an electric field thereby producing a ferroelectric hysteresis loop), antiferroelectric (i.e., materials which have an antiparallel alignment of polarization (or are non-polar) in the ground state but can be switched to a polar (parallel) order by an external electric field producing a reversible antiferroelectric-to-ferroelectric phase transition and a characteristic double polarization-electric-field hysteresis loop), and relaxor (i.e., chemically complex materials that exhibit a competition between short- and long-range interactions such that it produces a complex, dynamic polarization structure and exotic properties) materials.
In recent years, the use of epitaxial constraints has enabled the production of model versions of these complicated materials and the subsequent deterministic study of an array of physical phenomena that are now being widely considered for next-generation applications. Specifically, we will investigate the potential of ferroelectric materials for non-volatile, ultra-low voltage memory and logic applications including their use in ferroelectric-field-effect transistors, the realization of multi-state/neuromorphic function, and more. In turn, we will explore how antiferroelectric and relaxor thin-film materials can open the door to a new generation of thin-film based electromechanical, sensing, high-frequency, and capacitive-energy-storage devices. Along the way we will leverage advanced thin-film growth techniques to control the materials and to solicit new insights about their function, apply state-of-the-art characterization methods, including unique in operando studies under applied stimuli, to understand how materials function, and explore how such materials can be integrated and utilized in realistic device structures. We will try to introduce the listener to these complex materials and their potential for new applications – in effect working to motivate engineers to explore these materials. The discussion will range from the development of fundamental understanding of the physics that lies at the heart of the observed effects, to an illustration of routes to manipulate and control these effects, to the demonstration of rudimentary solid-state devices based on these materials.
(Invited) Advanced Electronic Characterization of Wide Band Gap Semiconductor Defects at the Nanoscale
Authors: Winchester Andrew , Pookpanratana Sujitra 
Published: August 2024

Wide bandgap materials such as gallium nitride (GaN) and gallium oxide (Ga2O3) are currently under development for realizing next-generation high power electronic devices beyond silicon. Vertical structures produced through homoepitaxial growth are preferred for scaling high-voltage devices, which places strict demands on the quality of bulk substrates. In particular, extended defects can propagate during epitaxial growth into the active areas of devices. Therefore, there is a need for identifying defects and determining their electronic properties at relevant nano- to micro- scale dimensions in order to disentangle their combined effects on macroscopic devices. Here, we use a combination of laser-based photoemission electron microscopy (PEEM) and electrical atomic force microscopy (AFM) methodologies to investigate the local electronic properties of surface defects in epitaxially grown GaN and β-Ga2O3. PEEM is a non-scanning electron microscopy technique where photoelectrons emitted by a surface illuminated by deep-ultraviolet light are imaged with nanometer-scale spatial resolution. The emitted photoelectrons are sensitive to the local electronic structure, making PEEM a powerful tool for evaluating electronic changes at length scales relevant for devices, and provides valuable information for identifying “killer” defects which must be minimized during device growth and processing.
The difficulty in producing large, low dislocation density bulk GaN substrates has led to longstanding issues with leakage current in diodes and transistor devices. We identify surface defects with different electronic properties in GaN epitaxy on different substrates using PEEM. We observe star-shaped defects on strain-patterned GaN substrates and elongated dark patches on growth ridges on ammonothermally grown GaN substrates. In both cases, the observed electronic changes in PEEM correlate directly with local electrical AFM measurements, revealing that local changes in the electronic structure at these defects results in altered electrical conduction.
In contrast, the development of large bulk Ga2O3 substrates has been more successful, yet the identification and influence of various defects on device performance is still largely unknown at this point. The topography of β-Ga2O3 epitaxy varies widely between growth methods and substrate orientations. For example, β-Ga2O3 by hydride vapor physical epitaxy lacks fine structure, yet has surface defects that regularly appear in parallel orientations. In β-Ga2O3 grown on different substrate orientations, we observe variations in the surface electronic properties using PEEM. For certain substrate orientations and growths, we find nanoscale variations in doping, while other orientations display micron-scale electronic inhomogeneity and defects. Our results demonstrate that laser-based PEEM can be a powerful tool for detecting electrically active defects, as well as evaluating the nanoscale electronic homogeneity of wide bandgap semiconductors.
Investigation of Neuromorphic Behaviors in Access Regions-Integrated Van Der Waals Heterostructures
Authors: Chen Lin , Lin Shu-Ping 
Published: August 2024

The emergence of neuromorphic devices has disrupted the traditional von Neumann architecture, providing a solution to the challenges of simulating neural parallel processing and power consumption in conventional computer architectures [1]. Access regions (ARs) are strategically created and positioned in proximity to source and drain electrodes, resulting in a channel that does not overlap with the floating gate (FG) [2]. In this study, we investigated ARs integrated van der Waals heterostructural field-effect transistor (AR-VH-FET) device, constructed by vertically stacking several 2D materials. Specifically, molybdenum disulfide (MoS2) served as a channel, hexagonal boron nitride (h-BN) as a tunneling layer, and graphene (Gr) as the FG. We conducted measurements on the transfer and output characteristics to characterize the electrical performance of the AR-VH-FET. Under a fixed VDS, with the application of positive and negative VBG as programming and erasing voltages respectively, we measured device retention and endurance. AR-VH-FET devices not only emulate basic neuromorphic functions but also replicate biological characteristics.

References

[1] Q. Wang, C. Zhao, Y. Sun, R. Xu, C. Li, C. Wang, W. Liu, J. Gu, Y. Shi, L. Yang, Synaptic transistor with multiple biological functions based on metal-organic frameworks combined with the LIF model of a spiking neural network to recognize temporal information, Microsystems & nanoengineering 9(1) (2023) 96.
[2] T. Sasaki, K. Ueno, T. Taniguchi, K. Watanabe, T. Nishimura, K. Nagashio, Material and device structure designs for 2D memory devices based on the floating gate voltage trajectory, ACS nano 15(4) (2021) 6658-6668.

Figure 1
Rapid Detection of Staphylococcus Epidermidis Using Electric-Double-Layer (EDL) Field-Effect Transistor (FET) Biosensors with Loop-Mediated Isothermal Amplification
Authors: Su Yi-De , Wang Yu-Lin , Chiu Chia-Lin , Thokchom Rohan , Tseng Huan-Wei , Kalaimani Vishal Mani , Lin Chia Kai 
Published: August 2024

Staphylococcus epidermidis is a Gram-positive bacterium which commonly grows in human skin, nasal passages, respiratory tract, intestinal tract, air, and water. Although it is harmless to healthy individuals, immunocompromised patients are at risk of infection, which can lead to severe symptoms. With the increased reliance on antibiotics in hospitals, the antimicrobial resistance of Staphylococcus epidermidis has also risen, pointing out a challenge in clinical treatment.
Therefore, the diagnosis of this bacterium has gained significant attention. The aim of this experiment is to detect bloodstream infections (BSIs) in the shortest possible time. The study is intended to be implemented in hospitals to provide a more convenient method for medical professionals to conduct screenings. The approach involves screening for the most common disease sequence, ssDNA, followed by sequential detection of corresponding cDNA, plasmids, and bacteria. To detect bacteria with the least amount of bacteerial load, a novel isothermal amplification method called Loop-mediated isothermal amplification (LAMP) is employed to increase the concentration of DNA of BSIs bacteria before measurement. The overall time required for this process doesn’t exceed one day, significantly increasing speed for the detection of blood-borne bacteria in hospitals. The core mechanism of this platform involves the use of electric-double-layer-gated field-effect-transistors (EDL-gated FETs) to amplify the gate voltage changes generated when the ssDNA binds with complementary DNA. These voltage changes are then converted into numerical values for analysis and interpretation.
Currently, the research results show that this biomedical sensor can detect concentrations ranging from 1fM to 1pM. With the assistance of LAMP, it has successfully achieved a concentration of approximately 1yM (10-24 M) and detected with EDL-gated FETs. The experiment was also carried out step by step on simulated clinical specimens. The experiments have found successful serum nucleic acid amplification methods that provide excellent detection limits. Compared with other biomedical sensors in the past, it not only has lower detection limits but also brings features such as faster, more convenient, and more portable.
Keywords: EDL, FET, Staphylococcus epidermidis, Biosensor, LAMP

Figure 1
(Invited) Battery-Free Wearable and Implantable Electronics for Chronic Disease Management
Authors: Niu Simiao 
Published: August 2024

60% of Americans live with at least one chronic disease. These diseases and their associated comorbidities are now the leading causes of death in the United States. The effective management of complex chronic diseases requires body-wide, long-term, accurate, and continuous monitoring of multiple physiological signals from wearable and implantable devices to precisely determine the pathological state. Wearable physiological signal monitoring can dramatically reduce the demand for physician visits and increase patients' engagement and treatment adherence rates. Specifically, battery-free wearables and implantable electronics reduce device volume and mechanical stiffness, significantly improving wear comfort, which is highly desirable for next-generation wearable and implantable electronics. However, battery-free wearables and implantable electronics still face many challenges, mainly wireless energy and data transfer. To address these challenges, my research has been involved in the exploration of rational system design concepts, material and device fabrication innovation, and tailored algorithms to enable smart battery-free wearables and implantable electronics targeting next-generation chronic disease management.
Here, I would like to discuss two of my developed technology platforms to elaborate on the concept of battery-free wearable and implantable systems. First, I will describe an RFID-based body area sensor network technology platform. This technology uses electromagnetic waves and RF antennas as energy and data transmission media and has broad applications in sleep tracking, workout monitoring, chronic wound healing, and inflammation management. Second, I will describe a triboelectric transducer-based implantable battery-free device. This technology platform uses ultrasound waves and triboelectric transducers as energy and data transmission media and has broad applications in implantable sensing. Overall, the developed technology platforms can assess multiple health outcomes and treatment responses to various chronic diseases. Ultimately, this technology will help reduce the burden of chronic diseases, lower medical costs, and provide a better quality of life for patients. (1,2,3,4)
References:
1. "A Wireless Body Area Sensor Network System Based on Stretchable Passive Tags". Nature Electronics 2019, 2, 361.
2. "High-Frequency and Intrinsically Stretchable Polymer Diodes". Nature 2021, 600, 246-252.
3. "Wireless, closed-loop, smart bandage with integrated sensors and stimulators for advanced wound care and accelerated healing". Nature Biotechnology 2023, 41, 652-662.
4. “An Ultrasound-Driven Implantable Wireless Energy Harvesting System Using Triboelectric Transducer”. Matter 2022, 5, 4315-4331.
Rapid Detection of Methicillin Resistant Staphylococcus Aureus (MRSA) Using Electric-Double-Layer (EDL) Field-Effect Transistor (FET) Biosensors
Authors: Tseng Huan-Wei , Lin Chia Kai , Kalaimani Vishal Mani , Thokchom Rohan , Su Yi-De , Wang Yu-Lin 
Published: August 2024

According to the latest statistics and analysis by American researchers based on the data from 195 countries worldwide, it has been found that one person in every five people died due to sepsis. The annual death caused by sepsis reaches up to eleven million people, and the number of deaths from sepsis is even higher than those from cancer. We believe that the detection of MRSA is necessary.
Staphylococcus aureus is the most common pathogen of sepsis. Methicillin-resistant Staphylococcus aureus (MRSA) or Multiple-resistant Staphylococcus aureus is a distinct strain of Staphylococcus aureus. It has mecA gene which codes for penicillin binding protein 2a (PBP 2A) that will remain active under beta lactams antibiotics. This gives bacterial the ability to grow under concentrations of beta-lactam antibiotics which leads to MRSA's resistance to almost all the different penicillin-type antibiotics including methicillin and other beta-lactamase-resistant penicillins.
To detect MRSA in the shortest possible time, we adopt field-effect transistor (FET) biosensor for the real-time detection of binding reactions between DNA probe and cDNA. We select DNA probe sequence of mecA to be the aptamer and immobilize probe DNA which are complementary to the target cDNA on the sensor. This process allows DNA strands to attach to the gold surface. After that, we detect the binding reaction of DNA probe and cDNA by analyzing electrical response of field-effect transistor (FET). We can observe that the Id current changes after cDNA hybridizes with DNA probe.
In conclusion, in our research results, Field-effect transistor (FET) biosensor can detect concentration ranging from 1fM to 1pM. In addition, we can achieve other advantages such as more portable, higher sensitivity, real-time monitoring capability, and lower detection limits. With this rapid detection procedure, we can do early diagnosis and treatment, thus improving the quality of human life.

Keywords: FET, EDL, Aptamer, DNA, MRSA

Figure 1
New Charged Interfaces for Energy Conversion and Catalysis
Authors: Fan Feng Ru 
Published: August 2024

Charged interfaces are key areas for charge transfer and chemical reactions. Studying these interfaces at the microscopic level, especially in constructing and characterizing specific structures, understanding charge transfer, and managing chemical reactions, is crucial but challenging. Our work focuses on three innovative interface structures: solid/solid triboelectric, liquid/gas electrified, and solid/ultrathin heterojunction interfaces. We have achieved significant insights into the charge transfer mechanisms within these electrified systems and effectively controlled catalytic reactions at these interfaces.
Key findings include:

Development of new concepts for contact electrification and electrostatic-induced coupling at solid/solid interfaces, leading to novel applications in energy conversion and catalysis. We introduced the concept of mechanical-electric-catalytic reactions based on triboelectric interfaces and achieved direct synthesis of hydrogen peroxide through friction-catalysis under normal conditions.

Effective control of reaction kinetics and selectivity in charged microdroplet liquid/gas electrified interfaces by adjusting parameters like droplet evaporation rates and electric field characteristics. This approach led to efficient production of hydrogen peroxide and selective conversion of carbon dioxide.

Precise atomic-level construction and sub-nanometer characterization of solid/ultrathin heterojunction interfaces, exemplified by gold/graphene interfaces. This included the development of a gold/ultrathin palladium/single-layer ruthenium structure, enabling in-depth study of hydroxylation reactions and the influence of palladium interlayers on ruthenium's catalytic efficiency.
(Invited) Application of Nanostructure for Improving the Interfacial Interactions between Sensing Surface and Targeted Particles
Authors: Lin Shu-Ping 
Published: August 2024

Various interfacial interactions, encompassing screened Coulomb (electrostatic double layer) forces, Lifshitz-van der Waals forces, hydrophobic/hydrophilic interactions, as well as steric, chemical, morphological, and roughness effects, have been confirmed to play a crucial role in governing the interaction between target particles and the sensing surface. Small protrusions on the sensing surface can induce substantial variations in the surface’s interaction with the target analytes based on the extended Derjauin-Landau-Verwey-Overbeek (DLVO) theory. 1 Here, indium tin oxide coated vertical nanowires served as nanostructure to investigate interfacial interactions between the sensing surface and targeted analytes. Analyzing the ratio of particle size to asperity size on the sensing surface within the extended DLVO theory revealed that surface roughness can provide sufficient interfacial interactions with target analytes, thereby enhancing the electrical sensing performance. Upon immersing the nanostructural sensing surface in an analyte solution, electrical signals undergo a significant shift owing to alterations in the surface potential at the interface between the functionalized sensing surface (such as antibodies or chemical functional groups) and the analyte solution. 2, 3 These observations highlight the critical role of nanostructure on the sensing surface, particularly with adequate surface roughness, in significantly improving sensing performance by facilitating effective interaction of the surface with the target analyte based on the extended DLVO theory.
References:

Huang, X.; Bhattacharjee, S.; Hoek, E. M. V., Is Surface Roughness a “Scapegoat” or a Primary Factor When Defining Particle−Substrate Interactions? Langmuir
2010,
26 (4), 2528-2537.

Lin, S.-P.; Lee, W.-J.; Sun, M.-C.; Yang, Y.-H.; Vinzons, L. U.; Lin, Y.-M.; Wei, Y.-T., Nano-Brush Structure for Rapid Label-Free Differentiation of Alzheimer’s Disease Stages and Direct Capture of Neuron-Derived Exosomes from Human Blood Plasma. ACS Applied Materials & Interfaces
2023,
15 (48), 56478-56489.

Yang, Y.-P.; Lu, Y.-L.; Kumar Gupta, A.; Lin, S.-P., Real-Time Impedimetric Detection of Cardiac Troponin I Using ITO-Coated Vertically Aligned Silicon Nanowires. Mater. Lett.
2022,
311, 131575.

Figure 1
Comprehensive Characterization of Porous Transport Electrodes with SEM, XPS, and Tof-SIMS
Authors: Stelmacovich Genevieve , van Eijk Lonneke , Foster Jayson , Walker Michael , Ding Lei , Zhang Feng Yuan , Paxson Adam , Pylypenko Svitlana 
Published: August 2024

Advancements towards more efficient design and manufacturability of polymer electrolyte membrane electrolyzers include recent efforts to better integrate the porous transport layer (PTL) and adjacent anodic catalyst layer (CL), forming the porous transport electrode (PTE). It is well known that characterizations of the PTL alone, especially when combined with a protective coating, present numerous challenges. The PTE structure is even more complex, and it is difficult to comprehensively characterize all components and interfaces. In prior work, we established Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) as a characterization technique for the PTLs coated with protective coatings. This work demonstrates ToF-SIMS as a powerful technique for the characterization of PTLs integrated with CLs.
A series of sintered Ti PTLs were first coated with protective Pt coatings and then coated with various IrOx and IrRuOx catalysts via electrodeposition. Prepared PTE samples ranged in catalyst loadings and catalyst composition. Selected samples were also subjected to annealing post-treatments to further modify catalyst composition. X-ray photoelectron spectroscopy (XPS) was conducted to identify surface chemical speciation and states of the catalysts. ToF-SIMS analysis was conducted using Cs in both positive and negative modes to identify chemical species, including Ir, Ru, and their oxides as a function of catalyst layer depth. These two methods were complemented by Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy (SEM- EDS) analysis to evaluate morphology and distribution of catalysts. This comprehensive physical and chemical characterization of the PTEs provides insights that are useful for the characterization of as produced, modified, and degraded PTE samples.