通过砷取代调控黑磷带隙用于高性能光电探测器件

多层黑磷的带隙(~0.33 eV)覆盖~3.7微米光谱范围,在红外应用方面有巨大潜力.然而进一步降低带隙使其可用于远红外器件仍面临挑战.此外,黑磷材料及器件饱受空气稳定性差的困扰.因此,我们提出了同系物砷取代的策略,实现了对黑磷带隙的调控和稳定性的增强.通过优化化学气相传输的生长参数,我们制备出砷含量可控的毫米级黑磷母体.经扫描隧道显微镜和能谱分析,砷原子随机嵌入黑磷的主晶格中并保留了原有几近完美的晶格排列.对于60%砷含量的多层黑磷,其电学带隙降低至~0.16±0.02 eV并伴随强的p型掺杂.受益于较小的晶格畸变和强掺杂效应,基于砷取代黑磷的光电器件表现出高达约882 mA W^(-1)的光响应率,远超未取代的黑磷基光电器件(约314 mA W^(-1)).更为重要的是,砷取代的黑磷器件在暴露大气环境(温度~20℃;湿度~33%)48小时后未表现出明显的氧化迹象.本文为开发黑磷基、可长时间运行的光电探测器和光调制器件提供了新途径.

Lifting surface reconstruction of Au(100)by tellurium adsorption

The Au(100)surface has been a subject of intense studies due to excellent catalytic activities and its model character for surface science.However,the spontaneous surface reconstruction buries active Au(100)plane and limits practical applications,how to controllably eliminate the surface reconstruction over large scale remains challenging.Here,we experimentally and theoretically demonstrate that simple decoration of the Au(100)surface by tellurium(Te)atoms can uniquely lift its reconstruction over large scale.Scanning tunneling microscopy imaging reveals that the lifting of surface reconstruction preferentially starts from the boundaries of distinct domains and then extends progressively into the domains with the reconstruction rows perpendicular to the boundaries,leaving a Au(100)-(1×1)surface behind.The Au(100)-(1×1)is saturated at~84%±2%with respect to the whole surface at a Te coverage of 0.16 monolayer.With further increasing the Te coverage to 0.25 monolayer,the Au(100)-(1×1)surface becomes reduced and overlapped by a well-ordered(2×2)-Te superstructure.No similar behavior is found for Te-decorated Au(111),Cu(111),Cu(100)surfaces,nor for the decorated Au(100)with other elements.This result may pave the way to design Au-based catalysts and,as an intermediate step,even potentially open a new route to constructing complex transition metal dichalcogenides.

Electrically driven single microwire-based single-mode microlaser

Engineering the lasing-mode oscillations effectively within a laser cavity is a relatively updated attentive study and perplexing issue in the field of laser physics and applications. Herein, we report a realization of electrically driven single-mode microlaser, which is composed of gallium incorporated zinc oxide microwire (ZnO:Ga MW) with platinum nanoparticles (PtNPs, d ~ 130 nm) covering, a magnesium oxide (MgO) nanofilm, a Pt nanofilm, and a p-type GaN substrate. The laser cavity modes could resonate following the whispering-gallery mode (WGM) among the six side surfaces by total internal reflection, and the single-mode lasing wavelength is centered at 390.5 nm with a linewidth of about 0.18 nm. The cavity quality factor Q is evaluated to about 2169. In the laser structure, the usage of Pt and MgO buffer layers can be utilized to engineer the band alignment of ZnO:Ga/GaN heterojunction, optimize the p-n junction quality and increase the current injection. Thus, the well-designed device structure can seamlessly unite the electron-hole recombination region, the gain medium, and optical microresonator into the PtNPs@ZnO:Ga wire perfectly. Such a single MW microlaser is essentially single-mode regardless of the gain spectral bandwidth. To study the single-mode operation, PtNPs working as superabsorber can engineering the multimode lasing actions of ZnO:Ga MWs even if their dimensions are typically much larger than that of lasing wavelength. Our findings can provide a straightforward and effective scheme to develop single-mode microlaser devices based on one-dimensional wire semiconductors.