氧化锌纳米线的界面掺杂及其光电性能调控研究

Achievements in the development of semiconductor integrated circuits have benefited a lot from the mature doping control of bulk and thin film materials; as well, for the important short-wavelength photonic and optoelectronic material, ZnO nanowire, the practical applications of nanowire optoelectronic devices and integration must be on the basis of an efficient and controllable doping process. The traditional bulk doping can not spatially separate impurities from carriers and excitons, which usually leads to strong carrier and exciton scattering by impurities and phonons and is therefore unfavorable for enhancing the carriers' mobilities and the exciton's radiative recombination efficiency; in addition, nanowire surface depletion layer and unintentional change of axial doping profile also significantly affect the carriers' transport, exciton's radiative recombination and their spatial uniformities in the axial direction. To circumvent the current difficulty, here we propose and develop a new interfacial doping strategy to construct core-shell type interface structures through a simple vapor-phase multi-step growth/deposition technique. Through design and manipulation of the interface electronic structure, we can obtain stable and controllable interfacial doping with the impurities spatially separated from the host lattice, carriers, and excitons; so that we can achieve successful manipulation and optimization of the carriers' transport, exciton's diffusion and relaxation processes (from macroscopic point of view, namely the electrical and optical performances). Through this project, we want to know how this interfacial doping can affect and be used to manipulate the exciton, electron, phonon characteristics and their coupling behaviors of individual ZnO nanowires; we also want to establish the general design principles and specific operations for ZnO nanowire interfacial doping. This study is useful for future realization of nanowire optoelectronic devices and integration by providing new, valuable design principles and methods, as well as the involved physical mechanisms. This strategy could also be widely adopted in the synthesis of other nanomaterials.

半导体集成电路的发展成就得益于对块材和薄膜的成熟的掺杂控制；对重要的短波长光子学和光电材料氧化锌纳米线，要实现纳米光电器件与集成的实际应用，同样必须建立在高效可控掺杂的基础上。传统的体掺杂不能使杂质和载流子、激子空间分离，对后者有较强的杂质散射和声子散射，不利于提高载流子迁移率和激子发光效率；此外，表面耗尽层和非刻意的轴向掺杂浓度变化，也会影响载流子输运、激子复合及其轴向均匀性。本项目提出并发展一种新的纳米线界面掺杂策略，利用简便的气相多步生长技术构筑核壳型界面结构，通过对界面能级结构的设计和调控，实现杂质与主体(晶格)、载流子、激子空间分离的稳定可控的界面掺杂，以达到对纳米线载流子输运、激子扩散与弛豫过程的有效调控和优化；揭示界面掺杂纳米线载流子、激子、声子及其耦合行为的规律和机制，总结纳米线界面掺杂的一般原理和具体方案，为实现纳米线光电器件与集成奠定物理基础并提供有价值的思路与方案。

传统的体掺杂不能使杂质和载流子、激子空间分离，对后者有较强的杂质散射和声子散射，不利于提高载流子迁移率和激子发光效率。本项目提出并发展了一种新的纳米线界面掺杂策略，通过对界面能级结构的设计和调控，实现杂质与主体(晶格)、载流子、激子空间分离的稳定可控的界面掺杂，以达到对纳米线载流子输运、激子扩散与弛豫过程的有效调控和优化。我们围绕界面掺杂氧化锌纳米线的界面高分辨表征方法学，激子复合与弛豫动力学，界面电子气量子输运行为的规律与机制这三个关键科学问题开展研究。提出并发展了界面掺杂氧化锌纳米线的气相多步生长及其界面原位调控技术，设计并制备出具有同质和异质界面夹心结构的核壳型氧化锌纳米线；系统地表征了界面掺杂氧化锌纳米线中的杂质和应变，内建电场/电势，以及载流子、激子和声子特性；重点研究了几种特殊设计的界面能级/电子结构对氧化锌纳米线的激子复合与弛豫，电（激子）声耦合过程的影响和调制；重点研究了界面掺杂氧化锌纳米线中低维界面电子气的量子输运行为及其机制；总结了氧化锌纳米线界面掺杂设计的一般原理和若干技术方案，为实现基于氧化锌纳米线的新型光电量子器件奠定了物理基础并提供了有价值的思路与方案。