基于半导体性单壁碳纳米管/富勒烯异质结的高性能透明全碳光电探测器

利用半导体性单壁碳纳米管(SWCNT)的高吸收系数、优异的光电特性和高载流子迁移率等特点,本文构筑了基于半导体SWCNT(sc-SWCNT)/富勒烯(C₆₀)异质结的透明全碳宽光谱的场效应晶体管光电探测器。该器件的大部分结构均由碳基材料组成,全碳异质结作为导电沟道材料,金属性SWCNT作为源漏电极,氧化石墨烯(GO)作为介质层,在可见光波段的透光率均高于80%。电学测试结果表明：该光电探测器表现出了较强的栅控能力,实现了从405～1 064 nm的可见光-近红外宽光谱响应,在5 mW/cm²的940 nm激光照射下,该器件光电响应率可以达到18.55 A/W,比探测率达到5.35×10¹¹ Jones,同时,表现出了优异的循环稳定性。     

氧化锌/金刚石薄膜异质结紫外光探测器

采用射频磁控溅射法在p型自支撑金刚石衬底上制备了高度c轴取向的n型氧化锌薄膜.研究了不同的溅射功率对氧化锌薄膜质量的影响.通过半导体特性分析系统测试了氧化锌/金刚石异质结的电流-电压特性,结果显示该异质结二极管具有良好的整流特性,开启电压约为1.6 V.在此基础上制备了结型紫外光探测器,并对其光电性能进行了研究.结果表...     

Ag纳米线增强硒微米管/聚噻吩自驱动光电探测器性能EI北大核心CSCD

自驱动光电探测器能够满足现代光电器件对节能和轻质的需求,但复杂的工艺和较高的成本限制了其进一步发展。本文采用旋涂法将硒微米管(Se-MT)和聚噻吩(PEDOT)制备成Se-MT/PEDOT异质结,其器件在350~700 nm波长下具有良好的光响应,无偏置电压下的响应度为8 mA/W(500 nm)。为了提高器件的光响应度,利用银纳米线(Ag-NW)修饰异质结制备Se-MT/PEDOT/Ag-NW,增强异质结在紫外-可见光区的光吸收并提高器件的光电性能。与Se-MT/PEDOT器件对比,Se-MT/PEDOT/Ag-NW器件在350~700 nm波长下的光电流数值整体上升,特别是在0 V偏压500 nm光照下,器件的响应度提升至65 mA/W(增强800%),开关比增强400%达到552,上升和下降时间明显下降至15 ms和28 ms。这一结果表明Ag-NW改性有机/无机异质结的方法可以应用于高性能光电探测器的制备。     

利用脉冲激光沉积外延制备CsSnBr3/Si异质结高性能光电探测器

钙钛矿半导体具有光吸收系数高、载流子扩散长度大和荧光量子效率高等优异物理特性,已在光电探测器、太阳能电池等领域展现出重要的应用潜力.但卤化铅钙钛矿的环境毒性和稳定性大大限制了该类器件的应用范围.因此,寻找低毒、稳定的非铅钙钛矿半导体尤为重要.利用锡元素替代铅元素并生长高质量的锡基钙钛矿薄膜是实现其光电器件应用的可行方案.本文采用脉冲激光沉积方法,在N型单晶硅(100)衬底上外延生长了一层(100)取向的CsSnBr₃钙钛矿薄膜.霍尔效应及电学测试结果表明,基于CsSnBr₃/Si半导体异质结在暗态下具有明显的异质PN结电流整流特征,在光照下具有显著的光响应行为,并具有可自驱动、高开关比(10⁴)以及毫秒量级响应/恢复时间等优良光电探测器件性能.本文研究结果表明利用脉冲激光沉积方法在制备新型钙钛矿薄膜异质结、实现快速灵敏的光电探测方面具有重要应用前景.     

具有光电倍增的宽光谱三相体异质结有机彩色探测器

实验研究了P3HT：PBDT-TT-F：PCBM三相体异质结活性层光谱拓宽及其材料混合度对探测器光电特性的影响以及陷阱辅助光电倍增的机理.在此基础上,获得了一个覆盖350–750 nm波长范围的彩色探测器.该探测器在-1 V低偏压下红绿蓝三基色的光响应度和外量子效率分别达到了470,381,450 mA/W和93%,89%,121%,比探测率均接近10¹² Jones,且各基色的特性参数最大平均相对偏差均小于20%,同时频率带宽分别达到了5,8,8 kHz.结果表明：在保持二相体异质结薄膜原有微观形貌下,掺入少量光谱拓宽材料可实现活性层吸收光谱的拓宽.利用能级陷阱中电子的辅助作用引入外电路空穴注入,可实现探测器光电倍增.通过调节三相材料的混合度可实现基色间探测能力的均衡性.     

基于AsP/MoS2异质结的偏振光电探测器

线偏振光的探测能力是评价偏振光电探测器件的重要指标。黑砷磷(AsP)是一种较为稳定的平面内各向异性材料,由于其面内结构各向异性,其对线偏振光较为敏感,在偏振探测领域有着重要的应用潜力。本文介绍了一种基于AsP/MoS2的高度偏振敏感光电探测器。由于AsP各向异性的光吸收、MoS2有效的载流子收集和输运能力以及范德华异质结对暗电流的抑制作用,该光电探测器实现了大于300的电流开关比,0.27 A/W的电流光响应度以及2×10^10 Jones的比探测率。更重要的是,此类光电探测器在638 nm波段实现了高达3.06二向色性比的偏振特性。这些实验结果表明AsP/MoS2异质结构在偏振光电探测领域有着广阔的应用前景。     

硒纳米花/聚苯胺异质结型宽光谱自驱动探测器的制备及性能EI北大核心CSCD

从节能、便携、微型化的角度看,在无电源供给的情况下能够自驱动的光电探测器更能满足现代电子设备的需求。本文采用原位聚合的方法制备了一种基于p型硒纳米花(Se-f)和p型聚苯胺(PANI)的新型异质结结构。Se纳米花结构的高表面积可以吸收更多的光能量,有利于空穴电子对的有效分离。PANI直接沉积于Se-f表面形成高质量的异质结,促进产生内建电场。Se-f/PANI器件在300~700 nm波长范围内均有良好的光电性能和自驱动特性,特别是在无偏压610 nm光照下具有最高的响应度(72.9 mA·W^-1)、良好的探测度(1.98×1012 Jones)以及快速的响应速度(上升时间8.6μs,下降时间3.24 ms)。这将为今后开发高性能自驱动有机/无机光电器件提供一个好的选择。     

基于PdSe2/GaAs异质结的高灵敏近红外光伏型探测器的制备和图像传感的应用

本文制备了一种基于PdSe₂/GaAs异质结的高灵敏近红外光电探测器,该探测器是通过将多层PdSe₂薄膜转移到平面GaAs上制成的. 所制备的PdSe₂/GaAs异质结器件在808 nm光照下表现出明显的光伏特性,这表明近红外光电探测器可以用作自驱动器件. 进一步的器件分析表明,这种杂化异质结在零偏电压和808 nm光照下具有1.16×10⁵的高开关比. 光电探测器的响应度和比探测度分别约为171.34 mA/W和2.36×10¹¹ Jones. 而且,该器件显示出优异的稳定性和可靠的重复性. 在空气中2个月后,近红外光电探测器的光电特性几乎没有下降,这归因于PdSe₂的良好稳定性. 最后,基于PdSe₂/GaAs的异质结器件还可以用作近红外光传感器.     

High-performance self-powered photodetector based on organic/inorganic hybrid van der Waals heterojunction of rubrene/silicon

Organic/inorganic hybrid van der Waals heterostructure with an atomically abrupt interface has attracted great research interests within the field of multifunctional electronic and optoelectronic devices. The integration of organic rubrene films with inorganic Si semiconductors can avoid the atomic mutual-diffusion at the interface, and provide the possibility of forming two-dimensional van der Waals heterojunction accompanied with the type-II energy band alignment, due to the transfer behaviors of majority carriers at the interface. In this study, the high-quality rubrene/Si van der Waals heterostructure with an electronically abrupt junction was prepared, and a self-powered photodetector was then constructed based on this hybrid heterojunction. The photodetector demonstrated an excellent switching response to the 1064 nm monochromatic light with large on/off current ratio of 7.0×10~3, the maximum photocurrent of 14.62 m A, the maximum responsivity of 2.07 A/W, the maximum detectivity of 2.9×10~(11) Jones, and a fast response time of 13.0 μs. This study offers important guidance for preparing high-quality rubrene/Si hybrid van der Waals heterostructure with desirable band alignment, and the designed heterojunction photodetector has an important application prospect in the field of multifunctional optoelectronics.     

Two-dimensional Janus van der Waals heterojunctions: A review of recent research progresses

Two-dimensional Jamus van der Waals(vdW)heterojunctions,referring to the junction containing at least one Janus material,are found to exhibit tuneable electronic structures,wide light adsorption spectra,controllable contact resistance,and sufficient redox potential due to the intrinsic polarization and unique interlayer coupling.These novel structures and properties are promising for the potential applications in eleetronics and energy conversion devices.To provide a comprehensive picture about the research progress and guide the following investigations,here we summarize their fundamental properties of different types of two-dimensional Janus vdW heterostruct ures including electronic struc-ture,interface contact and optical properties,and discuss the potential applications in electronics and energy conversion devices.The further challenges and possible research directions of the novel heterojunctions are discussed at the end of this review.     

Infrared photodetectors based on graphene van der Waals heterostructures

We propose and evaluate the graphene layer (GL) infrared photodetectors (GLIPs) based on the van der Waals (vdW) heterostructures with the radiation absorbing GLs. The operation of the GLIPs is associated with the electron photoexcitation from the GL valence band to the continuum states above the inter-GL barriers (either via tunneling or direct transitions to the continuum states). Using the developed device model, we calculate the photodetector characteristics as functions of the GL-vdW heterostructure parameters. We show that due to a relatively large efficiency of the electron photoexcitation and low capture efficiency of the electrons propagating over the barriers in the inter-GL layers, GLIPs should exhibit the elevated photoelectric gain and detector responsivity as well as relatively high detectivity. The possibility of high-speed operation, high conductivity, transparency of the GLIP contact layers, and the sensitivity to normally incident IR radiation provides additional potential advantages in comparison with other IR photodetectors. In particular, the proposed GLIPs can compete with unitravelling-carrier photodetectors.     

单壁碳纳米管受限空间内水的分布

碳纳米管管腔作为分子物质的纳米通道,其储存或输送水的能力具有重要研究价值.为了研究碳纳米管管腔受限空间对水分子团簇结构和分布的影响,本文采用分子动力学方法探究了管径、手性和温度对单壁碳纳米管管腔内水的结构和分布的影响.结果表明:在常温下,管径尺寸范围为1.018—1.253 nm的单壁碳纳米管管内易形成有序的多元环水结构,此范围以外碳纳米管管内难以形成水的有序结构;且随着管径尺寸增大,多元环水呈现由三元环至六元环的结构变化;范德瓦耳斯势分布分析表明,在上述管径范围内,水分子趋向于贴近碳纳米管管壁分布而形成水的有序结构.对比管径尺寸差别较小的碳纳米管,其手性对多元环水结构影响不大.多元环水结构的稳定性表现出温度依赖性,管径较大的碳纳米管内的多元环水的有序结构更易随温度升高而消失.     

Axisymmetric vibration of single-walled carbon nanotubes in water

A double shell-Stokes flow model is developed to study the axisymmetric vibration of single-walled carbon nanotubes (SWCNTs) immerged in water. In contrast to macroscopic solid-liquid system, a submerged SWCNT is coupled with surrounding water via the van der Waals interaction. It is shown that this unique feature substantially reduces viscous damping of the axisymmetric radial, longitudinal and torsional vibrations and significantly up-shifts the frequency of the radial vibration of an SWCNT. The study offers a theoretical explanation for the experimental observation and molecular dynamics simulations available in particular cases, and provides an efficient modelling tool and useful guidance for the study of the general dynamic behaviour of SWCNTs in a fluid.     

Theoretical calculations of thermophysical properties of single-wall carbon nanotube bundles

Carbon nanotube bundles are promising thermal interfacial materials due to their excellent thermal and mechanical characteristics.In this study,the phonon dispersion relations and density of states of the single-wall carbon nanotube bundles are calculated by using the force constant model.The calculation results show that the inter-tube interaction leads to a significant frequency raise of the low frequency modes.To verify the applied calculation method,the specific heat of a single single-wall carbon nanotube is calculated first based on the obtained phonon dispersion relations and the results coincide well with the experimental data.Moreover,the specific heat of the bundles is calculated and exhibits a slight reduction at low temperatures in comparison with that of the single tube.The thermal conductivity of the bundles at low temperatures is calculated by using the ballistic transport model.The calculation results indicate that the inter-tube interaction,i.e.van der Waals interaction,hinders heat transfer and cannot be neglected at extremely low temperatures.For(5,5) bundles,the relative difference of the thermal conductivity caused by ignoring inter-tube effect reaches the maximum value of 26% around 17 K,which indicates the significant inter-tube interaction effect on the thermal conductivity at low temperatures.     

The influence of surface effect on vibration behaviors of carbon nanotubes under initial stress

An analytical method is presented to solve the influence of surface effect on non-coaxial resonance of multi-walled carbon nanotubes embedded in matrix utilizing laminated structures model. Due to coupled van der Waals forces between adjacent tubes and surface effect exerted carbon nanotubes, the resonance frequencies and amplitude ratios of multi-walled carbon nanotubes under initial stresses show that the resonant characteristics of the multi-walled carbon nanotubes become complex and the numbers of vibrational modes do not keep increase under identical conditions after considering surface effects. The result obtained can be used as a beneficial reference for investigating the electronic and physical behaviors of carbon nanotubes.     

金属铈催化剂对单壁纳米碳管生长和结构的影响

研究了一种利用新型催化剂制备单壁纳米碳管（SWNTs）的工艺方法.将金属铈的氧化物（Ce O₂）与石墨粉按一定比例混合，填充到已打好孔的石墨棒中制成复合石墨电极 ，以其为阳 极在高温氦电弧中实施电弧放电.放电后的生成物经高分辨透射电子显微镜（HRTEM）和拉曼 光谱(Raman)的观察及分析表明：生成物中含有大量呈束状存在的单壁纳米碳管，管径均匀 ，平均直径为120—132nm. 关键词： 单壁纳米碳管 电弧放电 透射电镜分析     

一种基于碳纳米管的随机存储器

利用碳纳米管之间范德瓦耳斯力,设计了一种基于碳纳米管的可读写的随机存储器,研究了系统的双稳性,讨论了存储器的优点和可行性,并得出系统具有良好存储效应所应满足的条件 关键词： 碳纳米管 范德瓦耳斯力 动态随机存储器