Electrical and Structural characterization of single core-shell semiconductor nanowires

单核壳半导体纳米线的电学和结构表征

• 批准号: 413135326
• 负责人: Professor Dr. Ullrich Pietsch
• 金额: --
• 依托单位: Department of Physics
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/413135326?language=en
• 关键词: Electrical; Structural; characterization; single; core

The nanowire approach offers the possibility to form hetero-structures between highly lattice-mismatched systems, because the large surface to volume ratio allows relieving strain more effectively. Additionally, it offers the possibility to combine III V semiconductor materials with silicon which is a large step towards modern semiconductor technology. Understanding and control of electrical properties at the individual NW level is necessary for their integration into devices. We investigate GaAs/(In,Ga)As/GaAs and nip-doped (Ga,In)P/(Al,Ga)P radial core-shell NW heterostructures fabricated by MBE and MOCVD onto pre-patternede silicon (111) substrates for next generation optoelectronic devices. The performance of such structures is strongly related to crystallographic perfection which has significant impact on charge carrier mobility. In a core-shell system there might be several channels for charge carrier transport, such as the shell with lower band gap compared to the core, or along the oxidized surface of the outer shell. Additionally, it is suggested that structural defects like stacking-faults have strong impact on transport properties. We aim to understand the electrical properties of such radial core-shell NWs and their correlation to the particular defect structure. Conductivity measurements will be perfromed at single NWs in their as-grown geometry on the substrate, by means of FIB/SEM and low-temperature STM or AFM systems and by 4ppt STM using either tngsten nano-manipulator probe installed inside the FIB/SEM or the sharp metallic tip of the conductive AFM/STM. The I-V characteristics of selected core shell NWs will then be correlated to the detailed structural properties of the same nano objects: The phase balance betweeen wurtzite (WZ) and zincblende (ZB) units and structural defects within a NW will be determined by x-ray nano-diffraction and coherent diffraction imaging (CXDI) using synchrotron radiation at 3rd generation facilities PETRA III and the first 4th generation synchrotrin Max IV. Along with the ex-situ characterisation on single NWs,even in-situ X-ray diffrcation studies during simulataneous I-V measurement is planned. This in-situ experiments will be realized both at PETRA III and Max IV using a portable combined AFM/STM instrument, which has been designed specifically for the X-ray nano-focus beamline environment. Such in-situ studies will not only provide direct correlation of structural and electrical properties of individual NWs, but furthermore investigate the influence of local stress (applied by the AFM tip) and Joule´s heating(due to current flow) on NW structure and conductivity.

纳米线方法提供了在高度晶格失配的系统之间形成异质结构的可能性，因为大的表面积与体积比可以更有效地缓解应变。此外，它还提供了将 III V 半导体材料与硅结合的可能性，这是现代半导体技术的一大进步。了解和控制单个纳米级的电气特性对于将其集成到设备中是必要的。我们研究了通过 MBE 和 MOCVD 在预图案化硅 (111) 衬底上制造的 GaAs/(In,Ga)As/GaAs 和 nip 掺杂 (Ga,In)P/(Al,Ga)P 径向核壳 NW 异质结构，用于下一代光电器件。这种结构的性能与晶体学的完美性密切相关，这对载流子迁移率有重大影响。在核-壳系统中，可能存在多个用于载流子传输的通道，例如与核相比具有较低带隙的壳，或者沿着外壳的氧化表面。此外，有人认为堆垛层错等结构缺陷对输运性能有很大影响。我们的目标是了解这种径向核壳纳米线的电学特性及其与特定缺陷结构的相关性。将通过 FIB/SEM 和低温 STM 或 AFM 系统以及使用安装在 FIB/SEM 内部的钨纳米操纵器探针或导电 AFM/STM 的锋利金属尖端进行 4ppt STM，在基板上生长时几何形状的单个纳米线上进行电导率测量。然后，选定核壳纳米线的 I-V 特性将与相同纳米物体的详细结构特性相关联：纤锌矿 (WZ) 和闪锌矿 (ZB) 单元之间的相平衡以及纳米线内的结构缺陷将通过在第三代设施中使用同步加速器辐射的 X 射线纳米衍射和相干衍射成像 (CXDI) 来确定 PETRA III 和第 4 代同步蛋白 Max IV。除了单个纳米线的异位表征之外，甚至还计划在同步 I-V 测量期间进行原位 X 射线衍射研究。该原位实验将在 PETRA III 和 Max IV 上使用便携式 AFM/STM 组合仪器来实现，该仪器是专为 X 射线纳米焦点束线环境设计的。这种原位研究不仅将提供单个纳米线结构和电学特性的直接相关性，而且还将研究局部应力（由 AFM 尖端施加）和焦耳加热（由于电流）对纳米线结构和电导率的影响。