Nanoscale Advanced Materials Engineering via Localised Ion Doping

大多数先进的材料实际上是复合系统，其中每个部分都是专门定制的，以提供特定的功能，通常是通过掺杂。在电子设备中，这可能是p型或n型行为（导电正电荷或负电荷的偏好），在光学设备中，在给定波长发射光的能力（例如在光纤通信的红外线中），或在磁性材料中，基于磁场方向存储信息的能力。为了实现新设备，必须在给定的设备体积内增加功能密度。简单的微型化（即适应更多相同类型的设备，但尺寸更小）在纳米级范围内是有限的，不仅是众所周知的量子效应的出现，而且是在这种规模上控制材料工程的简单能力。例如，自组装方法可以创造0D（所谓的“量子点”或“人造原子”），1D（线状）和2D（片状）材料，具有独特的性能，但随后的控制和修改这些材料是非平凡的，尚未在许多情况下得到证明。该研究项目将支持建立一个世界领先的纳米级先进材料工程平台（P-NAME）设施，该设施将包含一个新工具，该工具将为我们设计和工程材料的能力提供根本改变所需的能力。该项目的具体目标是：-开发和验证P-NAME工具提供纳米级半导体材料掺杂的能力；-开发先进的掺杂材料加工方法，以激活掺杂原子和修复植入损伤；-制定合适的表征方案，以研究纳米级掺杂的影响；-演示通过纳米级掺杂实现的光子/自旋电子器件的示例。这些目标将使用最近委托的P-NAME工具来解决，该工具将在低能量和高剂量下实现具有多种离子种类的材料的高分辨率成像，掺杂和图像化，以局部工程材料，为先进材料工程提供纳米级功能的独特能力。离子种类包括B， P， As和Sb（用于Si），关键过渡金属（如Ti， V, Mn, Co, Ni）和稀土离子，以及其他技术上重要的物种（如Pd， Pt, Bi）将使用液态金属合金离子源提供。该工具将包含一个质量过滤器，以实现离子种类（和同位素）的分离，并采用模块化LMAIS概念设计，以实现源之间的有效转换。离子剂量和能量可以在空间上变化，从而可以获得和研究一个很宽的参数范围。离子剂量的范围从非常低（例如~10个离子）到通常用于电子掺杂半导体的水平（1014 - 1016个离子/cm2）甚至更高。离子的能量范围将从5 keV（使薄膜中的浅掺杂）到40 keV。更高的能量也可以通过使用双带电离子等使用ExB质量过滤器选择。掺杂物种类可多种多样，材料可在纳米尺度上原位合成，离子束光斑尺寸为20nm，可实现高精度掺杂。这与纳米精度样品处理和集成离子束控制一起提供了以前不可用的IBL能力。这将使预先沉积的纳米结构和器件（例如纳米线pn结，Si-photonics…）或使用IBL创建的原位结构的局部离子掺杂成为可能。验证将涉及测试样品的掺杂，并酌情使用HRTEM，太赫兹光谱和扫描探针光谱进行研究。这项工作将与其他机构合作完成。

Most advanced materials are actually composite systems where each part is specifically tailored to provide a particular functionality, often via doping. In electronic devices this may be p- or n-type behaviour (the preference to conduct positive of negative charges), in optical devices the ability to emit light at a given wavelength (such as in the infrared for optical fibre communications), or in magnetic materials the ability to store information based on the direction of a magnetic field for example. To enable the realisation of new devices it is essential to increase the density of functionality within a given device volume. Simple miniaturisation (i.e. to fit more devices of the same type but of smaller size) is limited in scope as the nanoscale regime is reached, not only by the well-known emergence of quantum effects, but by the simple capability to control the materials engineering on this scale. Self-assembly methods for example enable the creation of 0D (so called 'quantum dots' or 'artificial atoms'), 1D (wire-like) and 2D (sheet-like) materials with unique properties, but the subsequent control and modification of these is non-trivial and has yet to be demonstrated in many cases. This research project will support the establishment of a world-leading Platform for Nanoscale Advanced Materials Engineering (P-NAME) facility that incorporates a new tool which will provide the capability required to deliver a fundamental change in our ability to design and engineer materials. The specific objectives of the project are:- to develop and validate the P-NAME tool capability to deliver nanoscale doping of semiconductor materials;- to develop advanced doped materials processing methods in order to activate doped atoms and repair implantation damage;- to develop suitable characterization protocols to study the effect of nanoscale doping;- to demonstrate an exemplar photonic/spintronic device realized via nanoscale doping.These objectives are to be addressed using the recently commissioned P-NAME tool that will enable high resolution imaging, doping and patterning of materials with multiple ion species at low energies and high doses to locally engineer materials, giving a unique capability for advanced materials engineering providing nanoscale functionality on demand. Ion species including B, P, As and Sb (for Si), key transition metals (e.g. Ti, V, Mn, Co, Ni) and the rare-earth ions, and other technologically important species (e.g. Pd, Pt, Bi) will be provided using liquid-metal alloy ion sources. The tool will incorporate a mass filter to enable ion species (and isotope) separation and is designed using a modular LMAIS concept to enable efficient change over between sources.The ion dose and energy may be spatially varied to enable a wide parameter range to be accessed and studied. Ion doses will range from very low (e.g. ~10 ions) through to levels typically used to electronically dope semiconductors (1014 - 1016 ions/cm2) and higher. The ion energy range will be from 5 keV (to enable shallow doping in thin films) upwards to 40 keV. Higher energies are also available through the use of doubly charged ions etc. selected using the ExB mass filter. Dopant species may be varied and material synthesis performed in-situ on the nano-scale with an ion beam spot size of 20nm available for high-precision doping. This along with nanometer-precision sample handling and integrated ion beam control provide a IBL capability not previously available. This will enable localised ion doping of pre-deposited nanostructures and devices (e.g. nanowire pn-junctions, Si-photonics...), or of in-situ structures created using IBL.Validation will involve the doping of test samples and study using HRTEM, THz-spectroscopy and scanning probe spectroscopy as appropriate. This will be done in collaboration with others.