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236 results on '"Wang, Bingxiang"'

34. Solar-blind ultraviolet emission-detection monolithic integration of AlGaN multiple-quantum-well diodes via concentric ring-circle configuration.

Author

Chen, Yuxuan, Jiang, Ke, Wang, Bingxiang, Liu, Kexi, Wang, Xianjun, Ben, Jianwei, Zhang, Shanli, Lu, Shunpeng, Chen, Yang, Jia, Yuping, Liu, Mingrui, Sun, Xiaojuan, and Li, Dabing

Subjects
DIODES, LIGHT propagation, QUANTUM wells, FIELD emission, LIGHT emitting diodes, OPTICAL losses, ENERGY consumption
Abstract

AlGaN multiple-quantum-well diode-based solar-blind ultraviolet emission-detection monolithic integration system shows great application value due to its advantages of multifunctionality, secure communication, and anti-interference ability. To reduce the lateral optical propagation loss and improve the emitting light detection efficiency, we have proposed a concentric ring-circle configuration for the system, where the out-ring light-emitting diode is the emitter at 253 and 267 nm, and the inner-circle detector is the receiver. The out-ring light-emitting diode exhibits about twice the injection current at the same bias and slightly higher light output power at the same current due to better current spreading and sidewall light extraction compared to the conventional square–square configuration. Simultaneously, the concentric inner-circle detector maximizes the collection of the emitted light flux. Under the emission-detection mode for the monolithic integration system, compared to the conventional square–square configuration, the concentric ring-circle design presents an improvement in the ratio of emitter injection current to detector output photocurrent and higher output signal amplitude under the same transmission work mode, demonstrating the improved system energy and coupling efficiency. This design provides a potential approach to achieve low power consumption and high bandwidth in the monolithic integrated optoelectronic chips. [ABSTRACT FROM AUTHOR]

Published
2024
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41. Realizing high zero-bias gain in a GaN-based bipolar phototransistor through thin-base configuration for ultraviolet imaging.

Author

Wang, Bingxiang, Jiang, Ke, Zhang, Shanli, Chen, Yuxuan, Fang, Tong, Xie, Zhiwei, Ben, Jianwei, Chen, Yang, Jia, Yuping, Liu, Mingrui, Sun, Xiaojuan, and Li, Dabing

Abstract

Ultraviolet (UV) detectors with high gain at low bias are urgently demanded. In this study, a GaN-based UV bipolar phototransistor (BPT) with high zero-bias gain was obtained based on a n–p–i–n homo-structure. A thin-base structure is proposed to suppress excess hole recombination and, thus, to increase optical gain. The BPT with a 50 nm base showed zero-bias near-saturation photocurrent under UV illumination. The zero-bias photocurrent and detectivity increased with an increasing light power density of 52.6 A W−1 and 5.7 × 1012 Jones at 360 nm under an incident light power density (Pin) of 121 μW cm−2, corresponding to a gain of ∼180. Numerical simulations and BPTs with thick bases were employed to investigate the gain mechanism and response characteristics of the as-prepared BPT. A UV image was obtained using the thin-base GaN-based BPT and a scanning imaging method at zero bias, and the zero-bias sampling frequency was found to be ≥100 kHz. The GaN-based thin-base BPT design offers an effective and convenient strategy to achieve zero-bias high-gain UV detection for applications such as UV imaging. [ABSTRACT FROM AUTHOR]

Published
2024
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47. Late-Holocene changes in vegetation composition and fire regimes in the subalpine western Nanling Mountains in subtropic China.

Author

Quan, Mingying, Zhong, Wei, Wang, Xiaojun, Wang, Bingxiang, and Li, Tianhang

Subjects
VEGETATION dynamics, MIXED forests, MOUNTAIN forests, ENVIRONMENTAL engineering, CLIMATE change
Abstract

Understanding the responses of vegetation composition to climate, fire regimes and human disturbance is crucial to provide valuable insights to protect current and future ecosystems. However, relevant studies were poorly performed on the heavily forested montane areas in subtropic East Asia. In this study, we present pollen and charcoal records from a 95-cm long peat core in the subalpine Daping swamp in the western Nanling Mountains in subtropic China, to discuss the possible interactions among vegetation, fire, climatic change, and human activities in the late-Holocene. Our results suggest that the vegetation in the study area was composed of deciduous–evergreen mixed forests with few fire events during 3140–630 cal yr BP, and its changes were mainly controlled by climate with rare human impacts reflected by low concentrations of charcoals, low proportions of Poaceae pollen, and high AP/NAP ratios. After 630 cal yr BP, pollen data indicate an obvious shift from dense forests to more open landscape. The sharp increase of charcoal concentrations, the extremely low AP/NAP and increased Poaceae percentages suggest that this vegetation shift is not only impacted by the dry climate conditions, but also by the intensified deforestation due to enhanced human activities such as the slash-and-burn cultivation, etc. This study reveals a vital transitional timing from the natural to the superimposed anthropogenic forcing of vegetation composition and fire regimes at ~630 cal yr BP. Regional comparison of charcoal records indicates that the onset timing of intensified human disturbance in the inland montane areas is much later than that in the coastal areas in subtropic China. We infer the obstacle impacts of the montane terrain and the different responses of the dissemination of agriculture and enhanced population migration have played a crucial role in this asynchronous spreading pattern. [ABSTRACT FROM AUTHOR]

Published
2023
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