Growth, Fabrication, and Characterization of Novel Semiconductor Nanostructures

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Research into the properties of semiconductor materials is one of the foundations of our technological civilization. Semiconductor materials provide the backbone of electronic devices used to enable computers, wireless technologies, fibre optic communications, and solar power generation, among others. These devices have all been based on a detailed understanding of fundamental materials science and its potential for innovation.Nanowires are very thin wires of semiconductor materials with diameters in the nanometer range (10-9m) that have unusual properties by virtue of their very small diameters; for example, the properties and behaviour of electrons are different in very thin wires due to quantum effects. The high surface area-to-volume ratio of nanowires is both a potential advantage (e.g., for gas sensors) and a drawback (e.g., for light emitting devices and solar cells). In recent years, there has been significant progress in methods to form nanowires for use in a number of applications, including extremely high speed transistors, solar cells, gas sensors, high efficiency light emitters, and large surface area nanomaterials.The aim of this research proposal is to gain a clear understanding of the physics of semiconductor nanostructures, particularly nanowires, with the goal to use these novel structures in devices. Practical semiconductor devices rely on materials defects: on one hand, impurities must be introduced in order to control electrical conduction; on the other hand, certain defects, such as those that arise at the surfaces of materials, can have a negative effect. This can be problematic in nanowires, where the electrons are in close proximity to the surface. This proposal focuses on two key challenges in understanding the science of semiconductor nanowires. First, we propose to develop novel and controlled methods for the formation of specific nanowire structures that can be used in prototype device applications, such as solar cells and light emitting diodes. This includes developing methods to grow specific materials (GaAs, GaN, InAs, ZnO, and related materials) in structures that can be used to form device prototypes. Second, we will develop new ways of quantifying the role of surface and bulk defects on the behaviour of electrons and holes in semiconductor nanowires using advanced electron microscopy methods and low temperature optical spectroscopy. Our two-pronged approach will enable us to develop and test simple prototype nanowire device structures that will form the basis of future industrial applications.The proposed research will capitalize on our achievements and collaborations, and continue to set new directions in this field. This research program will train future leaders, equipped with expertise in semiconductor growth and characterization, and electron microscopy techniques, who will contribute to both research and industrial applications.