Improving the performance of a GaAs nanowire photodetector using surface plasmon polaritons

GaAs nanowires (NWs) are ideal materials for preparing near-infrared photodetectors owing to their high charge carrier mobility and direct band gap. Although the performance of GaAs NW photodetectors can be enhanced by surface passivation or doping, it still cannot meet the requirement for applications. In this paper we propose a method to greatly improve the performances of GaAs NW photodetectors by hot-hole injection via surface plasmon polaritons. In this case, the responsivity of a single GaAs NW photodetector is increased by a fact of 3.2 to 6.56 A· W^-1 by attaching capsule-like Au nanoparticles to its surface. This research uses an efficient route to improve the NW photocurrent, which is also important for the development of a high-performance near-infrared NW photodetecor.     

叶酸功能化介孔碳纳米球负载阿霉素的细胞靶向传递及可控释放

以粒径90 nm的介孔碳纳米球作为靶向传药载体, 采用酸化处理改进了材料表面的亲疏水性及在溶液中的分散性, 通过壳寡糖功能化, 并利用EDC-NHS将叶酸修饰到介孔碳纳米球表面. 通过共聚焦激光扫描显微镜及流式细胞仪对实验体系的系统研究, 结果表明基于叶酸功能化的介孔碳纳米球能够有效提高负载药物对于HeLa细胞的跨膜转运效率, 叶酸阳性表达的HeLa细胞对于叶酸修饰的介孔碳纳米小球的吞噬效率明显高于叶酸阴性表达的MCF-7细胞. 对HeLa细胞毒性的定量分析表明叶酸的靶向作用在提高介孔碳纳米球内吞效率的同时, 进一步提高了阿霉素对于HeLa细胞的毒性.     

Cr掺杂Si基稀磁半导体的制备及其磁学特性

采用Cr离子注入方法,在不同气体环境下退火制备了两种具有不同磁化率和居里温度的Cr掺杂p型 (111) Si基稀磁半导体样品.利用X射线衍射(XRD)、傅立叶变换红外( FT-IR)光谱和超导量子干涉仪(SQUID)对样品的晶体结构、化学键及磁学特性的变化进行表征.实验发现,该样品在H2气中退火后,氢原子钝化了Cr离子注入时引起的样品中的Si悬挂键缺陷(形成Si-H),增加了传导电子的长程相互作用,使样品的居里温度达280 K,远高于同一条件下在Ar气中退火样品的居里温度(100 K). 部分氢原子束缚了样品中的受主载流子,降低了磁化率,导致在低温区(小于50 K)H2气中退火样品的磁化强度小于在Ar气中退火样品的磁化强度.这为室温铁磁半导体的研制提供了实验依据.     

Synthesis and Optical Properties of ZnO Nanostructures

ZnO nanostructures with different morphologies were fabricated by changing the partial oxygen pressure. The structures, morphologies and optical properties of ZnO nanostructures were investigated by x-ray diffraction, field emission scanning electron microscopy and photoluminescence (PL) spectra at room temperature. All the samples show preferred orientation along the c-axis. The oxygen partial pressure and the annealing atmosphere have important effect on the PL property of ZnO nanostructures. The high oxygen partial pressure during growth of samples and high-temperature annealing of the ZnO samples in oxygen can increase oxygen vacancies and can especially increase antisite oxygen (OZn) defects, which degraded the near band-edge emission. However, the annealing in 1-12 can significantly modify the NBE emission.     

Normal Strain-Induced Tunneling Behavior Promotion in van der Waals Heterostructures

Van der Waals heterostructures(vdWHs) realized by vertically stacking of different two-dimensional(2D) materials are a promising candidate for tunneling devices because of their atomically clean and lattice mismatch-free interfaces in which different layers are separated by the vdW gaps. The gaps can provide an ideal electric modulation environment on the vdWH band structures and, on the other hand, can also impede the electron tunneling behavior because of large tunneling widths. Here, through ...     

ZnO缓冲层上定向ZnO纳米杆阵列的制备

利用Zn膜热氧化获得的非晶ZnO薄膜作为缓冲层,再采用Zn粉热蒸发工艺合成出定向、致密且直径较细(≈40 nm)的单晶ZnO纳米杆阵列,其阵列密度约为2.3×107mm-2.比较了在厚度不同的Zn膜所形成的ZnO缓冲层上生长的ZnO纳米杆形态,讨论了ZnO缓冲层表面形貌对ZnO纳米杆生长形态的影响.结果表明,随Zn膜厚度的增加,ZnO缓冲层从岛状大颗粒(0.5~1μm)并伴有密集小颗粒(<20 nm)状态变为连续薄膜,所得ZnO纳米杆从沿大颗粒表面无规则发散生长并伴小颗粒上的准定向生长转变成垂直于衬底的大面积定向生长,且纳米杆阵列也随着Zn膜厚度增加而变得定向、致密、和分布均匀.     

氧化锌纳米线的紫外光耦合增强场电子发射特性

本文采用热化学气相沉积方法制备氧化锌纳米线阵列, 研究氧化锌纳米线阵列在紫外光辐照下的场电子发射特性. 实验结果表明, 在紫外光辐照下, 氧化锌纳米线场发射开启电压降低, 发射电流明显增大. 机理分析认为, 氧化锌纳米线紫外光增强的场发射源自场电子发射与半导体耦合作用, 紫外光激发价带电子跃迁到导带和缺陷能级使发射电子数量增加, 同时, 光生电子发射降低了发射材料表面的有效功函数, 从而显著增强场电子发射性能. 氧化锌纳米线具有紫外光耦合增强场电子发射特性, 在光传感、冷阴极平板显示和场发射电子源等方面具有潜在的应用价值.     

ZnO多枝纳米棒水热法生长及其光学性质

以硝酸锌(Zn(NO3)2.6H2O)和六亚甲基四胺(C6H12N4)为原料,采用水热法在90℃生长出具有多枝六方纳米棒的ZnO纳米结构,运用X射线衍射(XRD)、扫描电子显微镜(SEM)和室温光致发光谱(PL)研究了ZnO样品的结构、形貌和光学性质.观察到多枝纳米棒的形成和生长情况,发现多枝ZnO纳米结构由单根纳米棒演化而来,不同发展阶段样品的PL谱呈现出强的黄绿光发射现象.样品的高斯拟合PL谱揭示了没有分枝的纳米棒样品中,氧间隙缺陷远多于氧空位缺陷,而分枝的ZnO样品中氧间隙缺陷与氧空位缺陷浓度的比值降低.