作为一种新型材料，半导体纳米线在揭示物理学基础理论以及光电子器件新应用等方面展示着巨大的潜力。作为纳米结构，由于尺寸受限所展现的量子限制效应往往具有奇特、优异的性能，在探索低维度器件物理机制方面显示出非凡的前景。同时纳米线由于尺寸减小引起的超高表面体积比，使得表面原子占比增加进而对器件性能的影响越加显著，引起了广泛的关注，被应用于气敏探测以及医疗检测等领域。同时，由于InAs基半导体纳米线具有高迁移率以及较窄直接带隙的特质，成为了制备高速器件以及红外光电器件的重要备选材料。因此，对于InAs基窄带隙半导体纳米线的制备以及纳米线光电子器件的研究显得尤为重要。 本论文主要研究了InAs、InGaAs纳米线的Au催化分子束外延生长以及嵌含有InGaAs量子点的GaAs纳米线有序阵列的选区金属有机气相沉积(MOCVD)生长。另一方面，基于纳米线场效应管(FET，field effect transistor)光电器件，研究了InAs纳米线表面态在光电探测中的作用，铁电材料／InAs纳米线复合结构器件的中波红外探测特性、铁电材料／InAs纳米线FET的非易失性可擦写存储特性以及InGaAs纳米线器件的近红外探测特性。主要的创新点与内容如下： 1.利用Au催化MBE方法制备了高质量的InAs纳米线，其表面有着2-3 nm的天然氧化层。将生长的InAs纳米线制备为背栅FET器件。当温度从室温降为77 K时，该器件由单极型n型转变为双极型。无论何种温度，当载流子类型为空穴时，器件在不同光子能量入射时显示为正光电导响应；当载流子类型变为电子时，器件在波长大于1060 nm的光子入射时表现为正光电导响应，在波长小于940nm的光子入射时表现为负光电导响应。验证了在纳米线导带之上存在由表面态引起的电子束缚能级，严重影响着器件的光电性能。通过在纳米线表面旋涂覆盖层，研究纳米线表面环境变化对器件性能以及响应速度的影响。结果表明吸附气体的存在会降低器件的响应速度。通过栅压调制纳米线表面态中电子束缚的状况，可以有效增强器件在近红外波段的光电响应。 2.制备了铁电材料P(VDF-TrFE)／InAs NW复合结构顶栅FET器件。利用铁电材料极化后产生的超强局域极化场来调控纳米线表面态中电子的分布以及实现能带的弯曲。在极化向上时，电子在静电场的作用下被束缚在纳米线表面态，被束缚的电子形成内建静电场进一步耗尽纳米线芯中的自由电子，使得器件处于超低的暗电流状态。相较于之前的工作报道以及商用器件，该器件在中波红外波段实现了最灵敏的光电探测响应率。在3.5 μm的光照条件下，InAs纳米线器件的响应率高达1.6×10⁴ A W⁻¹，探测率达到1.4×10¹²㎝·Hz〓W⁻¹，增益达到5.7× 10³。同时，超强的静电场产生了Franz-Keldysh效应，使得电子和空穴的波函数“隧穿”到带隙进而产生重叠。最终，将器件的探测范围拓展到带隙以下的4.3μm，并得到G=2.8×10².R=9.6 ×10² A W⁻¹以及D*=8.5×10¹⁰㎝·Hz〓W⁻¹。另一方面，在铁电材料极化场的作用下，电子完全被驱离表面态引起的电子束缚能级。当具有不同能量的光脉冲入射下，纳米线价带中的电子被激发到不同的能带位置，使得器件产生了不同的稳定电流输出。最后，InAs纳米线器件展示了一种新颖的非易失可擦写的光辅助存储特性。 3.利用Au催化MBE方法制备了高质量的InGaAs纳米线。通过详细的电子显微镜分析得到InGaAs纳米线具有特殊的自组装芯-壳(core-shell)结构。其中，纳米线的芯的组分是富In的，壳的组分是富Ga的。并且，沿着生长方向，芯中的Ga组分是逐渐减少的，壳中的Ga组分是逐渐增加的，芯与壳间的组分差异是逐渐增大的。这是因为与衬底上的InGaAs薄膜生长的竞争而形成富含In的纳米线芯。此外，纳米线芯和壳中的组分梯度是晶格弛豫的结果。对于组分梯度的变化做了详细的分析。最后，将生长的InGaAs纳米线制备为背栅FET器件，利用壳层的钝化保护作用，在近红外波段实现了优异的探测性能。 4.分别研究了GaAs纳米线阵列、GaAs／InGaAs异质结纳米线阵列、GaAs／InGaAs (QDs)／GaAs有序阵列的选区MOCVD生长。通过优化生长参数温度和V／III束流比，最终得到了均匀统一、周期分布的纳米线阵列。对纳米线生长的分子动力学进行了分析。然后进行了细致的微结构、组分分布以及荧光光谱测试。最后通过生长AlGaAs钝化层进一步降低纳米线表面的非辐射复合，增强了光学性能。 关键词：III-V族半导体，纳米线，表面态，光电子器件

 As a new material, semiconductor nanowires (NWs) show great potential in revealing the basic theory of physics and new applications of optoelectronic devices. As nanostructures, the quantum confinement effect in the size-limited direction often exhibits peculiar superior performance and shows extraordinary prospects in exploring the physical mechanism of low-dimensional devices. At the same time, NWs have an extremely high Surface area to volume ratio due to the reduced size. As the proportion of surface atoms increases, the influence on device performance becomes more and more important, and is widely used in gas sensing and medical testing. Moreover, InAs-based semiconductor NWs are important candidates for the fabrication of high-speed devices and infrared optoelectronic devices due to their high mobility and narrow bandgap properties. Therefore, the growth of InAs-based narrow-bandgap semiconductor NWs and the research of NW optoelectronic devices are particularly important. In this thesis, the growth of InAs and InGaAs NWs by Au-catalyzed molecular beam epitaxy and the growth of GaAs/InGaAs quantum dots ordered NW array by selective area metal organic vapor phase (MOCVD) were well studied. On the other hand, based on nanowire FET optoelectronic devices, the role of surface states of InAs NWs in photodetection was studied. Ferroelectric materials/InAs NW hybrid midwavelength infrared photodetectors, ferroelectric materials/InAs NW hybrid volatile rewritable memory and InGaAs near-infrared detectors were well studied. The main innovations and contents of this thesis are as follows: 1.Here we report single MBE-grown high quality InAs NW FET devices that can be converted from unintentionally-doped n-type unipolar to ambipolar when the temperature is reduced from room temperature (RT) to 77 K. The density of carriers can be modulated by the gate voltage. At 77 K and upon light illumination, the InAs NW ambipolar transistor based photodetector shows a novel phenomenon: the device exhibits a PPR behavior when it is p-type (back-gate voltage (Vbg) < 0 V); whereas when the device is n-type (Vbg > 0 V), its photoconductive behavior transforms from NPR to PPR when the incident light wavelength is increased from visible to short wavelength-infrared. Specifically, we show that there is an electron-trapping level caused by the InAs NW surface defect state above the conduction band, which plays an important role in its photosensitivity. A theoretical model based on charge transfer and electronic transition is proposed to explain this phenomena. Then, high-performance InAs nanowire detectors are well studied for sensitive detection in the near infrared. 2.Here we use ferroelectric poly (vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) as the top gate dielectric layer for the NW device. By utilizing the remnant polarization properties of this polymer layer, an ultrahigh local electrostatic field (～ 10⁹ Vm⁻¹) can be produced to control the surface states. When covered by the P(VDF-TrFE) polymer layer with one specific polarization direction, electrons are trapped at the surface states to produce a built-in electrostatic field in the NW, resulting in carrier depletion in the NW core. Such a condition leads to an ultra-low dark current thus a very good photoresponse in the mid-wave infrared region. More significantly, these trapped electrons at the surface also cause the energy band between the nanowire core and the native oxide layer to bend downward and the Franz-Keldysh effect, allowing sub-bandgap photodetection from InAs NWs extending the photoresponse beyond InAs band edge. In opposite polarization direction, the surface states of the nanowire are devoid of electrons, leading to large dark current and a unusual illumination wavelength dependent photoresponse (positive or negative). Furthermore, different stable levels of current output can be obtained and durably maintained when illuminated with different wavelength light pulses. Thus the "read" and "write" functions of the device can be achieved with light assistance, which can be potentially employed as an optically modulated nonvolatile memory device. 3.Here we grew epitaxial ternary InGaAs nanowires with high In concentration grown on GaAs {111} B substrates. Our detailed electron microscopy characterizations suggest that the grown ternary InGaAs nanowires have an extraordinary core-shell structure with In-rich cores and Ga-enriched shells, in which both nanowire cores and shells showed compositional gradient. It was found that In-rich nanowire cores are formed due to the Ga-limited growth environment, caused by the competition with the spontaneous InGaAs planar layer growth on the substrate that consumes more Ga than the nominal Ga concentration during the growth. Moreover, the composition gradient in the nanowires cores and shells is a result of strain relaxation between them. Our optoelectronic property measurements from prototype nanowire devices show a remarkable photoresponsivity under the near-infrared illumination. This provides a new approach for designing and realizing complex nanowire heterostructures for high-efficiency nanowire-based systems and devices. 4.The selected area MOCVD growth of GaAs nanowire arrays, GaAs/InGaAs heterojunction nanowire arrays, and GaAs/InGaAs (QDs)/GaAs nanowire arrays were investigated separately. By optimizing the growth parameter temperature and the V/III ratio, a uniform and periodic distribution of nanowire arrays was obtained. Molecular dynamics analysis of nanowire growth was performed. Detailed microstructure, compositional distribution, and photoluminescence spectrum were then performed. Finally, the growth of the AlGaAs passivation layer was carefully studied in order to further reduce the non-radiative recombination on the NW surface and enhance the optical properties of the NW. Key Words: III-V semiconductor, nanowire, surface state, optoelectronic device