Search

Core–shell heterojunction structure is a feasible approach to optimize the optoelectronic performance of devices by combining the advantages of different materials. In this work, GaN/AlN core–shell heterojunction microwire‐based photodetector (PD) has been fabricated, and appropriate epitaxy growth of AlN can improve the performances of PDs. Compared with pure GaN microwire device, the enhanced responsivity, sensitivity, detectivity, and external quantum efficiency value of 4160 A W−1, 1.88 × 107%, 3.93 × 1012 Jones, and 4.07 × 106% are obtained with 5 nm thick AlN. Meanwhile, a rise/decay time of 25/16 ms is possessed. In addition, the responsivity and detectivity are increased with an acceptable decrease in sensitivity when the exciting light intensity decreases. The effective advances of PDs are benefited from the increased Schottky barrier height, the built‐in electric field that promotes the separation of photogenerated electron‐hole pairs, and direct heteroepitaxial growth high crystal quality GaN/AlN core/shell structure, which will effectively passivate the surface of GaN microwire by covering AlN. This study sheds some light on fabricating high‐performance microwire‐based PDs. [ABSTRACT FROM AUTHOR]

Micro/nanowire light‐emitting diodes (LEDs) have inspired considerable research interests due to their potential applications in microdisplays and micro/nano‐optoelectronic integrated systems. Herein, a single InGaN/GaN multiple‐quantum‐well (MQW) microwire‐based flexible LED with high‐efficiency current injection and spreading is fabricated, and the performance modulation of the device by external strain is further studied. The results show that under external compressive strains, the output power is enhanced and the peak wavelength is blue shifted; on the contrary, the output power declines and the peak wavelength is red shifted under stretch strains. Compared with strain‐free devices, the flexible LED achieves the best performance at a − 1% compressive strain, with external quantum efficiency (EQE) increasing by 14.2% and efficiency droop reducing by 17.9%. The effective improvements are attributed to external strain‐induced piezoelectric polarization charges presented at local junctions/interfaces tuning the energy band. Herein, an efficient external modulation of light emission properties in a single InGaN/GaN MQW microwire LED is presented. [ABSTRACT FROM AUTHOR]

The Daguangbao landslide was the largest landslide triggered by the "5.12" Wenchuan Mw 7.9 earthquake. This landslide is among the few superlarge‐scale landslides of 1 billion m3 magnitude worldwide. As the landslide accumulation represents a potential hazard, long‐term monitoring and geological interpretation of the Daguangbao landslide is important to reveal the postsliding deformation characteristics and laws of this landslide type. To study the kinematic characteristics 10 years postearthquake, the landslide accumulation deformation was monitored in two stages using different data sets and processing methods. First, regarding the deformation 2 years postearthquake, we selected PALSAR‐1 data (21 October 2008 to 14 March 2011) and obtained the LOS (line of sight) direction time series deformation of the landslide using the Small BAseline Subset (SBAS) algorithm. Second, for the last 4.5 years of deformation, Sentinel‐1 data sets (26 November 2015 to 8 June 2020) in two ascending and one descending path are experimentally used. The vertical and east‐west deformations during this period are obtained. Thickness, topography, precipitation, and other factors are combined to analyze the landslide accumulation deformation. The landslide accumulation volume decreases under gravitational influence, shrinkage is accelerated under precipitation influence, and periodic fluctuations occur, which lag precipitation changes. The maximum vertical direction deformation rate is below 80 mm/year, and the deformation magnitude in the east‐west direction is approximately ±35 mm/year. Local deformation is still affected by the surface slope and aspect, and the overall landslide accumulation movement trend involves gathering of the eastern and western parts toward the middle. In the observation window, with the stabilization of accumulation, the deformation tends decrease. Key Points: Analysis of the decadal kinematic characteristics of the landslide shows that landslide deformation tends to be decreasingThe overall landslide accumulation movement trend involves gathering of the eastern and western parts toward the middleThe landslide accumulation volume decreases under gravitational influence, and shrinkage is accelerated under precipitation influence [ABSTRACT FROM AUTHOR]