Optoelectronic properties of bottom gate-defined in-plane monolayer WSe_2 p–n junction

Monolayer transition-metal dichalcogenides(TMDs) are considered to be fantastic building blocks for a wide variety of optical and optoelectronic devices such as sensors, photodetectors, and quantum emitters, owing to their direct band gap,transparency, and mechanical flexibility. The core element of many conventional electronic and optoelectronic devices is the p–n junction, in which the p-and n-types of the semiconductor are formed by chemical doping in different regions.Here, we report a series of optoelectronic studies on a monolayer WSe_2 in-plane p–n photodetector, demonstrating a lowpower dissipation by showing an ambipolar behavior with a reduced threshold voltage by a factor of two compared with the previous results on a lateral electrostatically doped WSe_2 p–n junction. The fabrication of the device is based on a polycarbonates(PC) transfer technique and hence no electron-beam exposure induced damage to the monolayer WSe_2 is expected. Upon optical excitation, the photodetector demonstrates a photoresponsivity of 0.12 mA·W~(-1) and a maximum external quantum efficiency of 0.03%. Our study provides an alternative platform for a flexible and transparent twodimensional photodetector, from which we expect to further promote the development of next-generation optoelectronic devices.     

Gap plasmon-enhanced photoluminescence of monolayer MoS_2 in hybrid nanostructure

Monolayer transition-metal dichalcogenides(TMDs) have attracted a lot of attention for their applications in optics and optoelectronics.Molybdenum disulfide(MoS_2),as one of those important materials,has been widely investigated due to its direct band gap and photoluminescence(PL) in visible range.Owing to the fact that the monolayer MoS_2 suffers low light absorption and emission,surface plasmon polaritons(SPPs) are used to enhance both the excitation and emission efficiencies.Here,we demonstrate that the PL of MoS_2 sandwiched between 200-nm-diameter gold nanoparticle(Au NP) and 150-nm-thick gold film is improved by more than 4 times compared with bare MoS_2 sample.This study shows that gap plasmons can possess more optical and optoelectronic applications incorporating with many other emerging two-dimensional materials.     

对凸形内部一类特殊点的研究

1 简介对于一个凸形,其内部任一点都能表示为凸形的某条弦的中点,但是对于一般的凸形,什么样的点能表示为凸形的某个内接中心对称凸多边形的中心?本文将对这个命题的推广进行讨论.以下为本文的主要结论.定理 设Ω为平面上的凸形,定义T为Ω的所有内接中心对称凸多边形中心构成的集合,则图形T的面积S(T)满足0≤S(T)≤1/4S(Ω)不等式左端等号成立当且仅当Ω为中心对称图形,不等式右端等号成立当且仅当Ω为三角形.(以下如无特殊说明,“凸形”,“中心对称图形”均指平面上的图形,且不包括直线或直线的一部分.)     

~(13)C固体核磁共振技术检测PM_(2.5)中的总有机碳质组分

建立了13C固体核磁共振技术检测PM2.5中总有机碳质组分的分析方法。针对大气气溶胶中有机质组分的复杂性,探索出较为快速检测PM2.5中总有机质组分的核磁共振分析方法,使样品无需进行繁琐的前处理即可获得可靠的化学结构信息。利用该方法获得了太原、新乡、广州冬季PM2.5样品中总有机物的化学结构信息。结果表明,该方法操作简单,检测较为快速,准确度较高,可以满足大气气溶胶总有机成分的检测要求。