Search

γ-GeSe has recently emerged as a promising material for electronics and optoelectronics due to its unique band structure and excellent electrical properties. However, controllable growth of γ-GeSe remains a significant challenge. In this work, the controllable growth of γ-GeSe microflakes (MFs) on a mica substrate was reported by vapor phase deposition via a rapid cooling strategy. The screw dislocation-driven growth behavior is confirmed based on systematic characterizations. Our experimental results demonstrate that the stress induced during the rapid cooling process is critical for the controllable synthesis of γ-GeSe MFs and corresponding growth mechanism was proposed. Our work provides a new experimental strategy for the controlled growth of γ-GeSe MFs, which is beneficial for constructing GeSe-based nanoelectronic and optoelectronic devices. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenides (TMDs) semiconductors are considered to be promising candidates for extending Moore's law. 2D TMDs with tunable wrinkled nanostructures can effectively modulate their optoelectronic properties. However, the controlled synthesis of large-area TMDs wrinkled nanostructures remains a major challenge. In this work, 2D WSe2 wrinkled nanostructures were prepared on soda-lime glass substrate by ambient pressure chemical vapor deposition based on the thermal mismatch-induced strategy. WSe2 wrinkled nanostructures can be further precisely controlled by adjusting the growth temperature and substrate thickness. In addition, the growth mechanism of WSe2 wrinkled nanostructures was revealed according to systematic experimental characterization. Corresponding results indicate that the photoluminescence and surface potential of WSe2 were associated with wrinkled nanostructures. The controllable synthesis strategy of 2D WSe2 wrinkled nanostructures has been developed, which can provide important experimental and theoretical support for exploring the applications of 2D wrinkled nanostructures in the field of strain sensing, optoelectronics, and nonlinear optical devices. [ABSTRACT FROM AUTHOR]

With the development of the photovoltaic industry; there will be an increasing demand for efficient, high-power density, and low-cost grid interface converters. Compared with two-level inverters, multilevel inverters have the following advantages: (1) lower device voltage ratings; (2) better output filtering spectrum; (3) lower electromagnetic interference (EMI) noise; and (4) higher switching speed capability. However, the complex switching circuit of the multilevel inverter will bring more parasitic inductance, resulting in severe switching overvoltage (ringing). Especially in order to reduce the cost of the inverter, using the long-loop modulation mode, the commutation loop will introduce more parasitic inductance, which will make the overvoltage more serious. Consider that commonly used overvoltage absorption schemes are effective only for overvoltage or suppression of oscillations. Therefore, a new overvoltage absorption circuit is proposed in this paper, which can not only alleviate the overvoltage and ringing phenomena but also suppress the effect of voltage jumps during low-frequency switching on high-frequency input voltage. This overvoltage absorption circuit is characterized by low overvoltage, fast ringing damping, and minimum capacitance. Experiments and simulations are conducted to verify the effectiveness of this overvoltage absorption circuit using a three-level ANPC inverter as a prototype. The results show that the proposed overvoltage absorption circuit can significantly reduce the overvoltage level, shorten the oscillation time, and reduce the voltage difference between the upper and lower DC bus capacitors. [ABSTRACT FROM AUTHOR]

Plant phenology refers to cyclic plant growth events, and is one of the most important indicators of climate change. Integration of plant phenology information is crucial for understanding the ecosystem response to global change and modeling the material and energy balance of terrestrial ecosystems. Utilizing 24 552 in situ phenological observations of 24 representative woody plant species from the Chinese Phenology Observation Network (CPON), we have developed maps delineating species phenology (SP) and ground phenology (GP) of forests over China from 1951 to 2020. These maps offer a detailed spatial resolution of 0.1 ∘ and a temporal resolution of 1 d. Our method involves a model-based approach to upscale in situ phenological observations to SP maps, followed by the application of weighted average and quantile methods to derive GP maps from the SP data. The resulting SP maps for the 24 woody plants exhibit a high degree of concordance with in situ observations, manifesting an average deviation of 6.9 d for spring and 10.8 d for autumn phenological events. Moreover, the GP maps demonstrate robust alignment with extant land surface phenology (LSP) products sourced from remote sensing data, particularly within deciduous forests, where the average discrepancy is 8.8 d in spring and 15.1 d in autumn. This dataset provides an independent and reliable phenology data source for China on a long-time scale of 70 years, and contributes to more comprehensive research on plant phenology and climate change at both regional and national scales. The dataset can be accessed at 10.57760/sciencedb.07995 (Zhu and Dai, 2023). [ABSTRACT FROM AUTHOR]