Combining the advantages of low-dimensional and wide-gap semiconductors, InGaN quantum dots (QDs) are widely investigated as a candidate material for high-efficiency micro-LEDs. In this work, plasma-assisted molecular beam epitaxy (PAMBE) was used to grow self-assembled InGaN QDs for the fabrication of green micro-LEDs. The InGaN QDs have a rather high density of over 3.0×1010 cm−2 and show good dispersion and relatively uniform size distribution. A green LED with the size of 300 μm × 300 μm based on InGaN/GaN multi-quantum dots (MQDs) was fabricated. In addition, the preparation of micro-LEDs with different diameters (from 4 μm to 20 μm) and arrays of them with an emission wavelength of 537 nm have been finished. The luminescence tests show that InGaN QD-based micro-LEDs have excellent wavelength stability with the increase of injection current density, which is attributed to the shielding effect of QDs on the polarized field. This performance is of great significance for full-color micro-LED displays.
Biosensors based on carbon nanotube (CNT) thin-film transistors (TFTs) have outstanding potential for ultrasensitive and label-free DNA detection. However, at present, the sensing mechanisms of the all-carbon-nanotube biosensors with metallic CNTs as electrodes are still controversial. In this work, a platform is established for universal DNA detection. By analyzing the biosensor responses obtained by passivating the channel, electrodes and contact of the biosensors, respectively, the sensing mechanisms can be clearly investigated. It is found that the electrostatic gating is dominant, while the Schottky barrier modulation plays a relatively minor role, where the Schottky barrier height is co-modulated by the adsorbed DNA in the channel and electrodes.
Nanophotonic multispectral absorbers and their enhanced optoelectronic performance have been studied in the research areas of photonics. The graphene-based quasi-photonic structures has amended the progress in this area. In this paper, the temperature tunable absorption was explored numerically using the proposed graphene-based phase change material (PCM) nanocomposite cavity in the photonic structure. This work observes higher multiband absorption in the infrared spectrum with thermal tuning and resonant frequency switchable with variation of composite material. The design procedure of cavities improves higher quality factor (Q) and Full-Width Half-Maximum (FWHM) compared to other literature with the inclusion of graphene as a defect. The temperature-dependent graphene-based nanocomposite cavity in the proposed structure varies absorption peaks with changes in defect layer thickness, chemical potential of the graphene layer, and angle of the incident light. The performance of the structure was also studied in terms of absorption behavior under oblique incidence, enhanced Q-factor and FWDM with blue shift resonant frequency under different polarizations are observed. These observations can be used for designing optical filters and narrowband optical absorbers.
Feedback-controlled electromigration method has been known to fabricate the atomic junction by controlling the quantized conductance on the Au nanowires. We demonstrated a real-time prediction of the quantized conductance on the Au nanowires dynamically inferred by reservoir computing on a real-time operating system. As a result, the root mean squared error in ballistic regime of the proposed system is 0.414. We believe that our system makes a valuable contribution to the fabrication of nanoscale devices in that it introduces the real-time prediction under running processes.
While there have been extensive reports in literature regarding the synthesis of porous silicon layers using electrochemical anodization for their use in different applications, systematic studies regarding the influence of the substrate dopant concentration and the electrolyte composition on the pore dimensions have not not been extensively investigated. In this work, we have systematically looked at the influence of dopant concentration and different electrolyte compositions on the pore dimensions of the porous silicon layer, along with varying input current density and reaction time.
Non-destructive patterning of low-dimensional materials has always been a challenge. An etching-free patterning method for high-density carbon nanotube (CNT) network has been proposed based on a wettability modulation method. By adopting this method, we have realized high-resolution patterns of CNT films, which have been uniformly formed on the wetting regions with precise boundaries. A flexible thin-film transistor array has been further realized, which shows excellent electrical performance with on/off current ratio of 10 4 as well as subthreshold swing of 280 mV/dec. This high-efficiency, high-resolution, and etching-free patterning approach of CNTs holds great promise for numerous potential applications in flexible and stretchable electronics and provides general solution for the low-temperature low-dimension material fabrications of advanced electronics.
Probabilistic bits (p-bits) can be viewed as tunable random number generators (RNGs), whose stochasticity coupled with their tunability makes them enablers for an emerging class of applications, including probabilistic computing. Their tunability is the feature that makes them unique to conventional RNGs. This paper studies the tunability range of existing p-bit designs reported in the literature, highlighting that existing designs have a limited input voltage range within which the p-bit’s stochastic response can be tuned, on the order of sub 0.5 V. This may greatly limit their scalability in large p-bit networks. Accordingly, this work proposes several variant p-bit designs that enable a wider input voltage tunability range and a more continuous response for p-bits. The designs employ both bipolar and continuous stochastic MTJs, and demonstrate an enhancement in the tunability range beyond 4 V (close to half of the supply voltage range).
The ability to quickly solve combinatorial optimization problems is essential for improving society and industry. For solving the problems, we present extraction-type majority voting logic (E-MVL) that purposely discards the interaction between the spins by scheduling a parameter, called sparsity. In this paper, the intrinsic computation time of E-MVL is estimated by using step-to-solution (STS) which evaluates the performance independent of implementation. We show that the E-MVL can explore the ground state to the Sherrington-Kirkpatrick model essentially faster than highly optimized simulated annealing (SA). These results indicate that E-MVL is more effective for optimization problems than SA.
With the development of the Internet of Things (IoT), new sensors and signal processing elements that consume near-zero power to operate on resonance, have high tunability and small form factor are necessary. The ultralow mass and large resonance tunability make resonant two-dimensional (2D) nanoelectromechanical systems (NEMS) suitable for ultrasensitive mass, force and biomolecular sensing, radio-frequency (RF) front end, and strain-tunable devices for memory and computing. Among the 2D materials, transition metal dichalcogenides (TMDCs) have ultralow mass, sizable bandgap, large Young’s modulus, and high strain limit, thus the 2D TMDC resonators only require picowatt level of power for sustaining the strong and stable resonance operations, have intriguing electromechanical coupling properties, have high frequency, and are highly tunable by strain. In this manuscript, we summarize the recent advances in 2D TMDC NEMS resonators, and show their potential applications. These TMDC resonators open new opportunities towards new types of sensors, RF signal processing elements, and computing devices that require near-zero power to operate on resonance, and at the same time, have wide dynamic ranges and tuning ranges.
In this work, we investigate the back-end-of-line (BEOL) compatibility of the TiN/Hf1-xZrxO2 (HZO)/TiN thin-film capacitors by exploiting the effect of sputtering power, ZrO2 content and process pressure. The variation of double remanent polarization (2Pr) suggests a crystal phase transformation in the HZO film when the sputtering power is altered. A change in the dielectric constant also supports this behavior. After tuning the process pressure, we could lower the required thermal budget for crystallization to 400°C, which is thermally compatible with BEOL processes. Moreover, the optimal sputtering parameters could reach 2Pr of 36 μC/cm2 with an endurance of up to 107 cycles. High 2Pr and good endurance achieved with low-temperature annealing is a breakthrough for sputtered HfO2-based thin films and shows a promising future for integrating sputtered HZO into BEOL processes.
Silver-based flexible transparent conductors (FTC) such as silver nanowire (AgNW) networks and nano-structured oxide–metal–oxide (OMO) are promising alternative materials to the indium-tin oxide (ITO). However, the weatherability and long-term reliability of the silver-based nano-structures strongly rely on surface passivation and protective overcoating technologies. Research on the outdoor durability of Ag-based FTCs is essential to establishing guidelines for optimized encapsulation and design strategies. In this study, spin-coated AgNW networks on glass substrate and commercial OMO on polyethylene terephthalate (PET) substrate have been exposed outdoors inside and outside an under-glass exposure box. Results indicate that high moisture brought from violent rain damages AgNWs significantly. The OMO nano-structures on the other hand are robust against adverse weathering conditions, but the embrittlement of aged PET substrate provokes the propensity of surface cracking on the protective oxide layers of OMO. This study provides a scientific basis for developing Ag-based FTCs for outdoor applications.
In this paper, we first introduced a miniaturized dual excitation laser-coupled intravascular ultrasound transducer with both a piezoelectric stack and a laser ultrasound transducer, which can generate a low-frequency (425 kHz) and high-frequency (7.2 MHz) dual excitation waves for thrombolysis. The prototype transducer can generate peak-negative pressure (PNP) of about 3.0 MPa with 100 V pp input voltage and 8.5 MPa with 1mJ laser energy input, respectively. The in-vitro thrombolysis showed improved clot mass reduction (61.74 ± 3.15 %) and clot lysis speed (63.12 ± 4.35 mg/min) of dual-excitation ultrasound treatment compared to piezo or laser-generated ultrasound alone treatment.
The aim of this communication is to discuss the possibility of using the innovative plasma source that we have developed recently, namely the "Space-Time Plasma Steering Source", as a versatile space-time deposition method. More precisely, we focus on the space-time control capabilities of time reversal plasmas over large and complex 3D surfaces. Simultaneous ignition of several plasmas by time reversal is also experimentally demonstrated. These unprecedented control capabilities of plasmas could lead to the development of an original and versatile method allowing the patterning of complex 2D or 3D structures on large areas.
In this paper, we were interested from a qualitative point of view, to the mechanisms of charge injection in Vertical Organic Field Effect Transistor structures (VOFETs) with n-type organic material (N,N'-ditridecyl-3,4,9,10-perylenetetracarboxylic diimide (PTCDI-C13)). We developed structures based on perforated electrodes whose nature were varied: Gold/ITO/Silver. We were also able to qualitatively analyze the quality of the interface between the metal and the semiconductor material using a displacement current measurement technique.
Welcome to Sofia and the IEEE JVA 2006 Symposium on Modern Computing. The symposium features 3 keynote addresses and 38 invited and contributed papers in topic areas corresponding to the four tracks of the symposium – Information Systems and Grid Technologies, Advanced Algorithms and Applications, Complex and Intelligent Systems, and High Productivity Computing. It is particularly positive to see a number of young researchers’ studies included as papers in these proceedings, and we will have even more young colleagues presentations at the JVA 2006 Symposium Posters Session. In addition, tutorial lectures on the 3 of October and panel discussions are also part of the symposium program. This is a rich and diverse program, and I am confident that these presentations will bring interesting new perspectives to research in modern computing.
The conduction current flowing through silicon nitride-silicon dioxide stacked films under negative gate bias at high temperatures has been analyzed and the electron transport mechanism in the stacked films has been studied. The trap depth for electrons in the silicon nitride film used in this work was estimated to be 1.3 eV, which was deeper as compared to that for holes (~1.0 eV). Next, the trap depths for electrons and holes in silicon nitride films with two different N/Si composition ratios were compared. Both trap states for electrons and holes were deeper in the silicon nitride film with the higher N/Si composition ratio. The analysis of the conduction current through silicon nitride-silicon dioxide stacked films is useful to evaluate the energy depth of trap states for electrons existing in silicon nitride films.
Since the last ever ITRS report, published in 2015, acknowledged the end of profitable scaling (Moore's law) the industry's focus has shifted to packaging as the focus area to drive down cost, size and increase performance [1]. Heterogeneous integration was recognized as being the key vehicle to continue miniaturization. However, it requires the combination and close packing of vastly different materials like low CTE semiconductors (Si, SiC, GaN, etc.) with high CTE heat dissipation materials (Cu/Al) to prevent overheating. The very different mechanical properties have led to warpage, delamination and early failures and have become the limiting factors in yield and reliability. Therefore, heat dissipation and CTE have become the roadblocks to technological advancement in packaging: we need new materials with matching properties not currently available. Solutions were attempted in the past with WCu and AlSiC macro-composites with limited success. Issues like high density, limited CTE tailoring, challenging high temperature manufacture and lack of solderability prevented their widespread use. In an effort to solve this problem, we used nanotechnology to design materials with new properties that are not available in nature. We used our copper-based nanomaterial to create a materials system that allows precise CTE-tuning between 3–17 ppm while retaining the highest possible thermal conductivity. The ready flowability of the formulated paste precursor drastically improves processability at low temperatures (200–240 °C) in minutes allowing the use of a rapid injection molding process, enabling low-cost mass-production of near-net-shape parts. Importantly, it can be soldered to directly without additional metallization. This ActiveCopper (aCu) materials system can replace the copper coin technology and readily manufacture CTE-matched lead-frames, heat sinks/spreaders and heat pipes for maximum heat dissipation.
As new materials and designs are being investigated for the development of next generation semiconductor technology nodes [1], this work focuses on atomically thin two-dimensional (2D) transition metal dichalcogenide (TMD) materials for future transistor designs [2,3]. In such devices, the metallic phase of TMDs (T') can be used as the source and drain electrodes and the semiconducting phase (H) a...
Copper has been used throughout history for its antimicrobial capacity; long before any mechanisms were understood it was folk medicine. Today, there are over 500 copper alloys registered with the EPA for their proven antipathogenic capabilities. These materials are unique compared to traditional disinfectants because of their broadband activity, longevity and ability to self-sterilize. They have significant potential in healthcare, industrial, and commercial settings because they are non-specific and able to kill all pathogens tested thus far. However, in the past they have been hindered by their action timeline; conventionally available bulk coppers are highly oxidized and frequently have very low surface areas. We have developed a novel copper configuration that remains unoxidized and possesses an extremely high surface area, thus making it ultra-active against pathogens. The testing we have done makes a very promising case for our copper, ActiveCopper, to be used in settings that experience frequent contact and need to be disinfected frequently. It eliminates infectious agents in less than a minute and retains that ability for years. In this paper we explore the possible mechanisms behind its unprecedented action and exhibit our analyses of its characteristics.
