EXTRAORDINARY MAGNETORESISTANCE NANO SENSORS - FUNDAMENTAL ISSUES AND APPLICATIONS

该提案是两所英国大学帝国理工学院和兰开斯特之间的合作，他们希望联合收割机的努力和专业知识，以开发和利用非凡的磁阻（EMR）效应。EMR效应是当接近金属界面时半导体的电特性的四端测量。传感器的特性是由在这两种材料（金属和半导体）之间的界面处形成的混合器件产生的，这两种材料具有非常不同的电导率大小。磁阻增强是由于在低磁场下电流流过金属分流器，而在高磁场下电流流过半导体。这种增强被称为几何效应，MR取决于材料迁移率的平方。我们的工作将与EMR的发明者Stuart索林教授直接合作（他目前通过EPSRC授予EP/C511816结束日期8月8日作为帝国的访问学者获得支持）。索林教授已经表明，如果传感器被加工到纳米级，但以某种特定的方式，侧壁散射被引入，这使半导体保持在扩散极限（平均自由程小于器件长度），其中保留了上述器件概念。如果侧壁散射被移除，我们预期该装置将在弹道极限（平均自由程大于装置尺寸）下操作，并且将观察到完全不同的传感器特性。我们希望研究的正是这种交叉，我们有兴趣了解侧壁散射在多大程度上损害了不同晶片设计的材料的流动性，以及使MR效应最大化的精确条件。该提案的重点将是发展对单个纳米传感器的全面理解，并开发新型成像纳米阵列，这将作为一种高分辨率，快速数据采集成像工具对广泛的科学领域产生影响。也有一个基础科学的机会，因为EMR混合结构的传输特性在纳米级的研究很少，特别是在扩散和弹道传输之间的交叉制度。

This proposal is a collaboration between two UK universities Imperial College and Lancaster who wish to combine efforts and expertise in order to develop and utilise the Extraordinary Magnetoresistance (EMR) effect. The EMR effect is a four terminal measurement of electrical properties of a semiconductor when in close proximity to a metal interface. The sensor properties result from the hybrid device formed at the interface between these two materials metal and semiconductor with very different electrical conductivity magnitude. The magnetoresistance boost come about due to fact that at low field the electrical current flows through the metal shunt and at high magnetic field it flows through the semiconductor. The boost is know as a geometric effect and the MR depends on the square of the mobility of the material. Our work will be in direct collaboration with the inventor of EMR, Prof Stuart Solin (who is currently supported as a visiting Fellow to Imperial through an EPSRC grant EP/C511816 end date Aug 08). Prof Solin has shown that if the sensor is processed down to the nanoscale but in a certain particular way, side wall scattering is introduced and this keeps the semiconductor in the diffusive limit (mean free path less than device length) where these device concepts described above are retained. If the side wall scattering is removed we anticipate that the device will operate in the ballistic limit (mean free path greater than the device dimensions) and entirely different sensor properties will be observed. It is this cross over that we wish to study and we are interested to understand how much the side wall scattering impairs the mobility of the material for different wafer designs and the precise conditions to maximise the MR effect. The emphasis of the proposal will be to develop a comprehensive understanding of single nanosensors and develop new types of imaging nanoarrays which will have impact as a high resolution, fast data acquisition imaging tool pivotal for a wide range of scientific areas. There is also a basic science opportunity because the transport properties of EMR hybrid structures have been little studied at the nanoscale particularly in the crossover regime between diffusive and ballistic transport.