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Silicon–germanium heterostructures are a promising quantum circuit platform, but crucial aspects, such as the long-term charge dynamics and cooldown-to-cooldown variations, are still widely unexplored quantitatively. In this Letter, we present the results of an extensive bias cooling study performed on gated silicon–germanium quantum dots with an Al2O3 dielectric. Over 80 cooldowns were performed in the course of our investigations. The performance of the devices is assessed by low-frequency charge noise measurements in the band of 200 μHz to 10 mHz. We measure the total noise power as a function of the applied voltage during cooldown in four different devices and find a minimum in noise at 0.7 V bias cooling voltage for all observed samples. We manage to decrease the total noise power median by a factor of 6 and compute a reduced tunneling current density using Schrödinger–Poisson simulations. Furthermore, we show the variation in noise from the same device in the course of eleven different cooldowns performed under the nominally same conditions. [ABSTRACT FROM AUTHOR]

Hydrogen-terminated diamond surfaces, emerging as a promising two-dimensional (2D) electron platform with great thermal and electronic properties, hold great potential for the next-generation high power and high frequency field effect transistor (FET). However, ideal gate dielectrics with high crystallinity and defect-free surfaces are still largely elusive. In this work, using the contamination-free pickup transfer method, hexagonal boron nitride (h-BN) flakes were fabricated on top of the hydrogen-terminated diamond surface to serve as a gate material and the passivation layer. The morphological and optical characterizations revealed the formation of homogeneous and intimate interface between h-BN and diamond. Benefiting from the h-BN gate dielectric layer, the maximum drain current density, subthreshold swing, and on/off ratio of diamond FET are measured to be −210.3 mA mm−1, 161 mV/dec, and 106, respectively. Especially, the transport measurement shows an almost constant Hall mobility of around 260 cm2 V−1 s−1 in the hole density range of 2 − 6 × 1012 cm−2, suggesting the excellent gate controllability of h-BN. Our results indicate that h-BN could form high-quality interface with hydrogen-terminated diamond, paving the way for the development of diamond-based electronic applications. [ABSTRACT FROM AUTHOR]

There are still challenges in the precise control of microwave energy for the industrial production, one of which is the effective inhibition of microwave hotspots or thermal runaway during microwave radiation, which has become a long-standing problem for improving heating uniformity and further expanding applications. Nevertheless, the evolution process and the underlying mechanism of microwave hotspots in high-dielectric dimers within different applied dielectrics are not fully understood due to the difficulty of internal temperature measurement. In this Letter, an optical indirect observation method has been proposed to characterize the hotspots distribution inside the applied dielectric. The grapes with high relative permittivity have been selected, which are easy to cut and absorb microwave, to conduct an in situ investigation of microwave hotspots evolution for dimers in a domestic microwave oven using the thermal and optical imaging. The results show that with the increase in the relative permittivity of applied dielectric, the starting of microwave plasma is prevented, and the focused hotspots disappear. Most significantly, the heating uniformity of dimers in water is improved by about ten times compared to that in air. The reduction of the calculated focused energy density near the contact point verifies the weakening effect of applied dielectric on the microwave cooperative resonance of dimers and explains the experimental phenomenon. These findings can be directly applied to inhibit the formation of focused hotspots for dimers or even multi-particle systems during the microwave processing and also provide a better understanding for cooperative interaction of Mie resonances. [ABSTRACT FROM AUTHOR]

The energy density of dielectrics could be evaluated both via low-frequency P–E loop (quasi-static recoverable energy density, Wre) and fast discharge current (dynamic discharge energy density, Wdis). The value of Wdis represents the useful energy, which can be converted to electrical energy while most work about high-energy-density dielectrics is focused on enhancing Wre. In this work, we investigated the relationship between Wdis and Wre in (Pb1 − 3x/2Lax)[(Zr0.45Sn0.55)0.99Ti0.01]O3 antiferroelectrics. Tuning the phase transition properties could improve the fast discharge capability by reducing the difference between Wdis and Wre and accelerating the energy release rate. At 300 kV/cm, the composition with x = 0 has the highest Wre of 6.7 J/cm3 but a lower Wdis of only 4 J/cm3 and longer discharge time duration, indicating a "high-energy-density" (highest Wre) quasi-static performance but "low-energy-density" (lower Wdis) and slow discharge performance during fast discharge. A highest Wdis of 5.9 J/cm3 and power density were achieved in composition with x = 0.2 though with lower Wre. The various fast energy release performance was explained by their different domain mobility and phase switching behavior. Thus, purely pursing high Wre is with limitation and suppressing the difference between Wdis and Wre is with great significance. This work will give an approach for the development of energy storage dielectrics by connecting their fast discharge performance with polarization mechanism. [ABSTRACT FROM AUTHOR]

Bipolar plasticity for synaptic emulation of indium gallium zinc oxide thin-film transistors (TFTs) with HfOxNy–HfO2–HfOxNy sandwich-stack films as the gate dielectric was investigated. The postsynaptic current increased when a negative pulse train was applied to the gate of TFTs; when a positive pulse was applied, the postsynaptic current was reduced. This result is discussed based on the charge trapping/releasing process with the assistance of ferroelectric behavior of the enwrapped oxygen-deficient-HfO2 layer. The dual response of this synaptic transistor shows promising prospect in the mimicking of biological neurons. [ABSTRACT FROM AUTHOR]

For advanced electronic device applications including printable, flexible organic electronics and bioelectronics, it is crucial to develop novel dielectric materials with high dielectric strength and low-temperature processability compatible with plastic substrates for producing flexible and low-voltage organic thin-film transistors (OTFTs). Herein, we report the facile fabrication of rationally designed, high-capacitance hybrid gate dielectric films for low-voltage OTFTs on plastic substrates via a room-temperature solution process. To create room-temperature-processed gate dielectrics with high dielectric strength, we designed organic-inorganic hybrid gate dielectric films by including ZrOx networks as inorganic high-k oxide materials for obtaining large capacitance and 1,6-hexanediol diacrylate as a bifunctional UV cross-linking agent and a flexible organic component for increasing the density and flexibility of films and ensuring room-temperature processability. The UV cross-linked ZrOx-based hybrid composite films with a 15 nm thickness showed excellent dielectric properties with a leakage current density of ∼10−6 A/cm2 and a capacitance of 640 nF/cm2. The film surfaces were modified with hydrophobic self-assembled monolayers to match the surface energy of organic semiconductors for enhancing the OTFT performance. The utility of the hybrid dielectrics for flexible OTFTs was demonstrated by realizing pentacene TFTs on plastic substrates with a low operating voltage at –2.5 V, a high on/off current ratio of 105, a threshold voltage as low as –0.7 V, and a hole mobility up to 0.47 cm2 V−1 s−1, which are comparable to those performed on Si substrates. [ABSTRACT FROM AUTHOR]

An ultrathin, 5 nm, AlO film grown by atomic-layer deposition was used as a gate dielectric for amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). The AlO layer showed a low surface roughness of 0.15 nm, a low leakage current, and a high breakdown voltage of 6V. In particular, a very high gate capacitance of 70 nF/cm was achieved, making it possible for the a-IGZO TFTs to not only operate at a low voltage of 1V but also exhibit desirable properties including a low threshold voltage of 0.3 V, a small subthreshold swing of 100 mV/decade, and a high on/off current ratio of 1.2χ107. Furthermore, even under an ultralow operation voltage of 0.6 V, well-behaved transistor characteristics were still observed with an on/off ratio as high as 3χ106.The electron transport through the Al2O3 layer has also been analyzed, indicating the Fowler-Nordheim tunneling mechanism. [ABSTRACT FROM AUTHOR]

The continuous scaling and challenges in device integrations in modern portable electronic products have aroused many scientific interests, and a great deal of effort has been made in seeking solutions towards a more microminiaturized package assembled with smaller and more powerful components. In this study, an embedded light-erasable charge-trapping memory with a high-k dielectric stack (Al2O3/HfO2/Al2O3) and an atomically thin MoS2 channel has been fabricated and fully characterized. The memory exhibits a sufficient memory window, fast programming and erasing (P/E) speed, and high On/Off current ratio up to 107. Less than 25% memory window degradation is observed after projected 10-year retention, and the device functions perfectly after 8000 P/E operation cycles. Furthermore, the programmed device can be fully erased by incident light without electrical assistance. Such excellent memory performance originates from the intrinsic properties of two-dimensional (2D) MoS2 and the engineered back-gate dielectric stack. Our integration of 2D semiconductors in the infrastructure of light-erasable charge-trapping memory is very promising for future system-on-panel applications like storage of metadata and flexible imaging arrays. [ABSTRACT FROM AUTHOR]

We show that anisotropic negative effective dispersion relation can be achieved in pure dielectric rod-type metamaterials by turning from the symmetry of a square lattice to that of a rectangular one. Theoretical predictions and conclusions are verified by both numerical calculations and computer based simulations. The proposed anisotropic metamaterial, is used to construct a refocusing slab lens and a subdiffraction hyperlens. The all-dielectric origin makes it more straightforward to address loss and scaling, thus facilitating future applications in both the terahertz and optical range. [ABSTRACT FROM AUTHOR]

The behavior of stress induced leakage current (SILC) in thin HfOxNy films is investigated. Except for the H dispersive transport process, the electron trapping process is responsible for the SILC generation in HfOxNy dielectric. This trapping process is severely modulated by temperature, thickness, and stress polarity. The recovery of SILC also proves the influence of trapping process to SILC. [ABSTRACT FROM AUTHOR]

The interfacial structure for HfO2 dielectrics on Si (100) substrate was investigated using x-ray photoelectron spectroscopy. The Hf 4f binding energy changes with the depth, which confirms the presence of Hf–O–Si state. Together with the analysis of O 1s and Si 2p spectra, it is believed that the interfacial structure includes both SiOx and Hf silicates. The electrical measurement is also consistent with the above conclusions. According to the theoretical and experimental results, a cursory model of the interfacial structure was established: The main body is SiOx species, on the top of SiOx is HfSixOy species, and Hf silicides are embedded in the Hf silicates. [ABSTRACT FROM AUTHOR]

We present a method and results for measurement of electron density in atmospheric-pressure dielectric barrier discharge. The electron density of microdischarge in atmospheric pressure argon is measured by using the spectral line profile method. The asymmetrical deconvolution is used to obtain Stark broadening. The results show that the electron density in single filamentary microdischarge at atmospheric pressure argon is 3.05×1015 cm-3 if the electron temperature is 10 000 K. The result is in good agreement with the simulation. The electron density in dielectric barrier discharge increases with the increase of applied voltage. [ABSTRACT FROM AUTHOR]

A one-dimensional metamaterial is realized using three connected Ω rings printed back-to-back and reversed on two sides of a dielectric substrate. Both transmission and prism experiments are reported, yielding concordant results of the presence of a left-handed frequency band. Experiments show reduced losses and an enlarged left-handed frequency band. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]