The ultrafast spatiotemporal imaging of photoexcited electrons is essential to understanding interfacial electron dynamic processes. We used time- and energy-resolved photoemission electron microscopy (PEEM) to investigate the photoexcited electron dynamics at multiplex in-plane silicon pn junctions. We found that the measured kinetic energy of photoelectrons from n-type regions is higher than that from p-type regions owing to different work functions. Interestingly, the kinetic energy of outer n-type regions is higher than that of inner n-type regions, which is caused by the reverse bias induced by photoemission. Time-resolved PEEM results reveal different evolution rates of hot electrons in different doping regions. The rise time of the n-type (outer n-type) regions is faster than that of the p-type (inner n-type) regions. So, closed doping patterns can influence the electron spectra and dynamics at the micro-nano scale. These results help us to understand the ultrafast dynamics of carriers at in-plane interfaces and optimize optoelectronic integrated devices with complex heterojunctions.

A variety of infrared applications rely on semiconductor superlattices, including, notably, the realization of high-power, compact quantum cascade lasers. Requirements for atomically smooth interface and limited lattice matching options set high technical standards for fabricating applicable heterostructure devices. The semiconductor twinning superlattice (TSL) forms in a single compound with periodically spaced twin boundaries and sharp interface junctions and can be grown with convenient synthesis methods. Therefore, employing semiconductor TSL may facilitate the development of optoelectronic applications related to superlattice structures. Here, it is shown that InAs TSL nanowires generate inter-sub-band transition channels due to the band projection and the Bragg-like electron reflection. The findings reveal the physical mechanisms of inter-sub-band transitions in TSL structure and suggest that TSL structures are promising candidates for mid-infrared optoelectronic applications.

南矶湿地是江西省面积最大的湿地,对江西省的生态调节具有极大的影响.本文旨在通过分析鄱阳湖南矶湿地国家级自然保护区呈现出的保护问题,全面探求其深层次的制度和法律管理办法,提出多层面的解决措施,为南矶湿地保护提供法律上的依据.课题组对南矶湿地保护区管理局的管理、技术、饲养、野外作业人员等21名工作人员召开访谈会和进行问卷调查,分析了保护区工作人员基本信息、保护区的主要人为干扰、湿地保护法律法规及相关规章制度适用情况.结果表明:鄱阳湖南矶湿地国家级自然保护区受教育水平和整体管理水平较高,但仍存在一定的问题,如保护区经费预算不足,湿地的人为干扰较严重等.分析认为:可通过对立法的完善以及管理制度的改进对当前问题进行解决,如引进高水平人才,增加资金投入,设立专门的纠纷协调机构,建议加快全国性的湿地立法.

in fl uence the fi nal photovoltaic ef fi ciency of their cells. They show that concentration of the titanium source in the hydrothermal precursor solution

Due to the ability to manipulate photons at nanoscale, plasmonics has become one of the most important branches in nanophotonics. The prerequisites for the technological application of plasmons include high confining ability (λ0 /λp ), low damping, and easy tunability. However, plasmons in typical plasmonic materials, i.e., noble metals, cannot satisfy these three requirements simultaneously and cause a disconnection to modern electronics. Here, the indium arsenide (InAs) nanowire is identified as a material that satisfies all the three prerequisites, providing a natural analogy with modern electronics. The dispersion relation of InAs plasmons is determined using the nanoinfrared imaging technique, and show that their associated wavelengths and damping ratio can be tuned by altering the nanowire diameter and dielectric environment. The InAs plasmons possess advantages such as high confining ability, low loss, and ease of fabrication. The observation of InAs plasmons could enable novel plasmonic circuits for future subwavelength applications.

A new crystal of Er3+/Yb3+:Ca9La(VO4)7 was grown successfully by the Czochralski method. Its spectral properties were investigated in detail. The crystal has a strong absorption band near 980 nm with a full-width at half-maximum of 33 nm, which means that it is very suitable for InGaAs laser diode pumping. Based on the Judd-Ofelt theory, the intensity parameters and radiative lifetime were obtained. The fluorescence lifetime of the 4I13/2 level of the Er3+ ion is 4.28 ms. The emission cross sections of the Er3+ ion at 1533 nm calculated by the Füchtbauer-Ladenburg method are 0.86 × 10−20 cm2 and 1.08 × 10−20 cm2 for σ- and π- polarization, respectively. The results indicate that Er3+/Yb3+:Ca9La(VO4)7 crystal is a potential 1.5–1.6 μm laser material.

We report on the growth of single crystal InAs nanowires on Si/SiOx substrates by chemical vapor deposition (CVD). Both pure zincblende InAs nanowires and twin superlattice InAs nanowires are produced. We demonstrate that the morphology and crystal structure of these nanowires can be controlled by tuning the H2 carrier gas flow rate in a CVD furnace and show that highly selected growth of twin superlattice nanowires are achieved at high carrier gas flow rates. Our work provides a new route to grow and phase-engineer single crystal InAs nanowires for a wide range of potential applications.

The invention discloses a method for preparing InAs nanowires with specific morphology and crystal structure. According to the invention, through adjusting carrier gas flow rate, the morphology and crystal structure of the nanowires can be effectively controlled. The method provides a reference for realizing low-cost and high-efficiency InAs nanowire growth, and provides partial guidance in the aspect of CVD nanowire growth controllability. Also, the invention has important significance to further learning and researches of the nucleation and growth mechanism of twin crystal superlattice nanowires.

In this paper, a method to fabricate Silicon-on-Nothing (SON) MOSFETs using H+ and He+ co-implantation is presented. The technique is compatible with conventional CMOS technology and its feasibility has been experimentally demonstrated. SON MOSFETs with 50nm gate length have been fabricated. Compared with the corresponding bulk MOSFETs, the SON MOSFETs show higher on current, reduced leakage current and lower subthreshold slope.

隧道工程由于爆破施工使岩体产生大量的裂隙,形成介质中氡及子体的析出.文章根据氡及子体运移规律的研究,提出了合理调整地下通风和局部地段及时喷锚支护的方案,控制氡的扩散、渗流,确保地下隧道及地表环境不受污染.

In this paper, the influences of H-2(+) and He+ co-implantation on electric characteristics of MOSFETs are experimentally investigated. H-2(+) and He+ are implanted into crystalline silicon substrates at different doses with the incident energy of 40keV. The substrates are annealed in mixture gas of H-2 and N-2 (1:10) at 1100degreesC for 30 minutes. Transmission electron measurement on the samples shows that a dense voids layer has been formed in the substrates, which is called "nothing" layer. Afterward, on the top silicon film, n type MOSFETs, called SON MOSFETs, are fabricated with conventional MOS technology. Compared to bulk transistors, SON MOSFETs show lower off-state drain leakage and higher over drive capability. Besides, obvious kink currents are observed on the output curves. The experimental investigation implies that using H-2(+) and He+ co-implantation may form SOI-like structure devices in a single process flow so as to reduce SOI wafer cost.

In this paper a novel technique of Silicon-on-Nothing (SON) MOSFETs fabrication by H+ and He+ co-implantation is presented for the first time. This in-house technique is compatible with conventional CMOS technology and it can greatly alleviate the problems existing in the known techniques of SON devices. SON nMOSFETs with 50nm gate length have been fabricated and demonstrated in this paper. With the same process condition.. SON MOSFETs exhibit better performance than the corresponding bulk silicon. MOSFETs.