Departmental Seminar


Mr Naiyin Wang

Nanowires, representing one of the most important building blocks of nanoscience and nanotechnology, have been demonstrated to be important for both fundamental research and device applications. Still, this elongated 1D nanostructure faces many challenges in practical device applications in terms of synthesis, assembly, functionality, and fabrication processes. There are also greater demands on the flexibility of the geometry, uniformity, and structural and optical qualities of nanostructures to address these issues, which motivates the exploration of higher-order 2D and 3D nanostructure shapes. In this work, we focus on the investigation of InP nanostructures since InP is one of the most of important III-V semiconductors which has a direct bandgap, high electron mobility and is promising for optoelectronic applications. All InP nanostructures including nanowires and other more sophisticated shapes are grown by selective area epitaxy (SAE) technique using MOCVD.

In this seminar, I will firstly demonstrate highly uniform arrays of wurtzite (WZ) InP nanostructures with membrane-, prism-, and ring-like shapes, which are grown on the conventional InP {111}A substrate. Growth optimization including growth temperature and V/III ratio, shape transformation mechanism as well as structural and optical properties are studied. Furthermore, I will discuss in-depth investigation of InP nanostructures grown on other low-index InP substrates such as {100}, {110}, {111}B, {112}A and {112}B with their morphologies evolving from nanowire to nanomembrane. Novel double-layered InP nanomembranes with type-II band alignment are obtained. More importantly, from thorough analyses of these nanostructures, a unified growth model for SAE of InP nanoshapes is established, regardless of geometries and substrate orientations. Finally, I will present and discuss the result of InP/InAsP quantum well nanomembranes, which have excellent optical properties.

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