FUNCTIONAL NANOWIRES, NANOWIRE HETEROSTRUCTURES AND THREE-DIMENSIONAL NANOWIRE NETWORKS

The ITRS roadmap for the semiconductor industry has identified semiconducting nanowires as a possible route by whichthe size-scaling of Moore's Law can be extended to yet smaller dimensions. Nanowires could be used both as the logicelements and the memory elements in a future semiconductor technology with device dimensions below 10 nm. The fieldof nanowire research is therefore particularly active at present and can be expected to deliver real applications in themedium to long term.In this fellowship I will address two key issues which must be resolved if nanowire applications are to make an impact inthe electronics sector:(i) How can nanowires be interconnected to form useful circuits?(ii) What unique functional properties can be engineered into nanowires that can be exploited in applications?Experiments to address the first of these issues will focus on using organic scaffold deposition (OSD) for growth of three-dimensional metallic nanowire networks. In particular we will study the growth of magnetic nanowires using OSD with the ultimate aim of creating a three-dimensional magnetic storage medium for high-density computer memory applications.Experiments to address the second issue will concentrate on semiconducting and superconducting nanowires. For semiconducting nanowires we will use the established nanoparticle-seeded molecular beam epitaxy (NS-MBE) technique and extend it to a variety of III-V and II-VI materials. Using NS-MBE we will be able to modulate the properties of the nanowire along its length simply by changing the precursor material during growth. (This technique has already been demonstrated to result in atomically sharp materials interfaces in the InP/InAs system.) NS-MBE therefore gives us a toolkit for studying the role of reduced dimensionality on a number of functional materials and heterostructures, including (for example) dilute magnetic semiconductors and heterostructure photonic devices.Superconducting nanowires will be grown using focussed-ion-beam and OSD techniques. These nanowires, which display a range of new physical phenomena, will be studied for applications as single photon detectors for use in infra-red quantum key distribution systems and as quantum current standards.