Magnetically-Doped III-V Semiconductor Nanostructures

EPSRC：Daniel Blight：EP/R513131/1随着硅晶体管的尺寸和其他电路特征接近其物理极限，性能增长已经开始落后于摩尔定律，从引入新的工艺节点到这些节点的成本效益降低之间的时间增加。与此相关的两个关键挑战是：(I)随着更多的晶体管和其他器件的增加，在硅芯片内产生的热量不断增加，并且提取这种热量的难度增加，以及(Ii)器件中的长度尺度正在达到量子效应占主导地位的极限，并导致器件性能的崩溃。因此，对能够帮助保持器件性能增长的历史速率的替代技术进行了大量研究。在该领域显示出巨大前景的一个领域是自旋电子学领域，在该领域，电子的自旋被用作另一种自由度，为设备增加了新的功能。自旋是一种量子力学性质，载流子(如电子)的自旋被定义为向上或向下。这一性质与硬币的顺时针或逆时针旋转不同，因为量子力学允许电子同时携带“向上”和“向下”，直到测量完成。这提供了利用这一特性执行当前技术不可行的复杂计算的机会，同时还实现了额外的信息存储。重要的是，自旋可以通过一种材料，而不需要建立电流。因此，这种自旋电流不会通过电阻效应(由欧姆定律描述)来产生热，因此可以为器件中的热产生问题提供解决方案。因此，几十年来，能够显示自旋性质和转移等的材料的研究一直是人们非常关注的焦点。自旋的一个重要特征是它与磁场相互作用，因此人们开始在材料中掺入磁性掺杂剂(如锰)以提高其性能。这在低温下已经显示出一些令人印象深刻的结果，然而在室温(或更高温度)时的热效应通常意味着这些效应‘消失’。为了克服这个问题，为了产生在室温下运行的材料，最近的研究表明，在小型结构(纳米级)中，物理限制电荷载流子的效应可以增强相互作用，使得它们可以在更高的温度下被观察到。然而，在如此小的结构中掺杂磁性掺杂剂的任务是非常具有挑战性的。该项目将把多伦多在生产纳米线材料方面的世界领先专业知识与曼彻斯特开发的一种新材料掺杂能力结合起来，使单一离子(原子)能够掺杂到纳米结构中。这将为解决这一目标提供一条新的途径，即开发适合于实现室温自旋器件的材料。它还将提供研究量子效应的机会，未来量子效应可能提供传统半导体电子学的替代技术(例如量子计算)。安置将为曼彻斯特大学的博士生(丹尼尔·布莱特)提供机会，让他在多伦多大学花费更长的时间来开发纳米材料生长、器件制造、磁性掺杂和表征的协议。这一安排将构成相关团体和大学之间更大规模合作的基础，并将被用作未来资金申请、联合博士生名额和团体之间流畅的研究人员交流的基础，获得世界领先的专业知识和实验能力的障碍最小。

EPSRC : Daniel Blight : EP/R513131/1As the size of silicon transistors and other circuit features is approaching their physical limits, performance growth has begun to lag behind Moore's law with the time between the introduction of new process nodes increasing and the cost-effectiveness of these nodes decreasing. Two key challenges exist relating to this: (i) the increasing heat generated within silicon chips as more transistors and other devices are added and the difficulty in extracting this heat, and (ii) length scales in the devices are reaching the limit at which quantum effects become dominant and lead to a breakdown of the device performance.As a result there has been much research into alternative technologies that could help to maintain the historical rate of device performance growth. One field that has shown great promise in that area is the field of spintronics, where the spin of electrons is used as another degree of freedom, adding new capabilities to devices. Spin is a quantum mechanical property and charge carriers (e.g. electrons) possess a spin that is defined as either 'up' or 'down'. This property is not the same as the rotating spin of a coin for example which is either clockwise or anti-clockwise, as quantum mechanics allows the electron to carry both 'up' and 'down' at the same time until a measurement is made. This offers the opportunity to utilise this property to perform complex calculation not feasible by current technologies, whilst also enabling the additional storage of information. Importantly, spins can be 'passed' through a material without needing to establish an electrical current. Such spin currents therefore do not generate heat through the effect of resistance (described by Ohm's law) and therefore may offer a solution to the issue of heat generation in devices.Research into materials which are able to display spin properties and transfer etc. has been the focus of much attention as a result for a number of decades. One important feature of spin is that it interacts with magnetic fields and hence the doping of materials with magnetic dopants (such as manganese) to enhance their properties has been undertaken. This has shown some impressive results at low temperatures, however the effect of heat when at room temperature (or above) typically means these effects are 'lost'.To overcome this issue, with the aim of generating materials which operate at room temperature, recent work has indicated that in small structures (nanoscale) the effect of physically confining charge carriers in a structure close to their 'wavelength' can enhance interactions such that they may be observed at higher temperatures. However, the task of doping such small structures with magnetic dopant is very challenging. This project will combine the world-leading expertise in Toronto in generating nanowire materials with the development of a new materials doping capability at Manchester that enables single ions (atoms) to be doped into nanostructures. This will provide a new route to addressing this goal of developing materials suitable for realising room-temperature spin-based devices. It will also offer the opportunity to study quantum effects which in the future might offer an alternative technology to traditional semiconductor electronics (e.g. quantum computing).The placement will provide the opportunity for a PhD student (Daniel Blight) at the University of Manchester to spend an extended period of time at the University of Toronto to develop the protocols for nanomaterials growth, device fabrication, magnetic doping, and characterisation. The placement will form the basis of a much larger collaboration between the groups and Universities involved and be used as a basis for future funding applications, joint PhD studentships and the fluid exchange of researchers between the groups with minimal barriers to accessing world-leading expertise and experimental capabilities.