Theoretical And Experimental Research On Radial Heterostructure Nanowires

One-dimensional geometric characteristics of nanowires can form various functional nanoheterostructures by combine different materials together flexibly. Radial nanowire heterostructure is "core-shell" structure grown in the side of coaxial nanowire formed of different materials. It is one of the core structural units in the area of optoelectronic nanowire devices and has broad application prospects in the nanowire lasers, solar cells and other devices. Theoretical and experimental study of radial nanowire heterostructures has important guiding significance for the design, preparation of high performance nano-optoelectronics. This paper focuses on radial nanowire heterostructures. Results are as follows:1. By establishing heterojunction nanowire elasticity theoretical model, the relationship among the radius、the well thickness、the outermost barrier thickness and the lattice mismatch of the single radial heterostructure nanowire critical dimensions distribution have been analyzed. At a certain mismatch, there is a critical core radius. When growing smaller than the critical value, there will not form the dislocation. When the value is greater than the critical radius it can be controlled to form the dislocation by adjusting the outermost barrier thickness. In addition, bigger mismatch will result in the lower critical dimensions.2. Theoretical study of the critical dimensions of GaAs/InGaAs/GaAs nanowire core-multishell quantum well heterostructures has been done. The result shows that in most instances, the dislocation tends to form in the inner-side of the heterointerface. Only when the composition of Indium is very large or the core radius is very small, the dislocation will be form in the outer-side of the heterointerface. The difference with the "core-shell" structure is that the critical dimensions of the nanowire core-multishell quantum well heterostructures is determined by the stress field of the two interfaces and related to the parameters of the core radius and the outermost barrier thickness. For a given core radius, the critical dimension of the quantum well is smaller than the "core-shell" structure. Under certain conditions, the nanowire can be achieved without dislocation by controlling the nanowire core radius and the outermost barrier thickness. The simulated results are in good agreement with the experimental data.3. Au-assistant GaAs/InGaAs "core-shell" structure GaAs/InGaAs/GaAs nanowire core-multishell quantum well heterostructures are grown by using Metalorganic Chemical Vapor Deposition (MOCVD) and the morphology and structure features has been characterized. The simulated results are in good agreement with the experimental data. In addition, the electrode preparation process of a single nanowire radial heterostructures has been preliminary explored.