Final PhD Seminar

Epitaxial growth, optical properties and structural studies of GaN nanorods and related heterostructures

Ms Bijun Zhao
ANU

Group III-nitride nanorods are promising building blocks for high efficient optoelectronic devices thanks to their ideal bandgaps, high aspect ratio, and high crystal quality. By forming axial or radial heterostructures, the optical emission of GaN based nanorod could tune from the deep ultraviolet (AlN) to the near infrared (InN). Among these nanorods, self-assembled GaN wires are gaining increasing attention due to the simplicity in sample preparation and the foreign catalyst-free approach used for their synthesis. The self-assembled process is also highly practical for a range of applications that do not require precise positioning, such as single wire devices and flexible nanowire light emitting diodes (LEDs).

In this talk, I will present my work on self-assembled GaN nanorods grown on sapphire substrates using metalorganic chemical vapour deposition (MOCVD). This work focusses on the following topics: (i). Link between surface nitridation and changes in related crystal polarity and optical properties. We found that the nitridation process is highly important for controlling the morphology and polarity of the GaN nanorods. (ii). Detailed investigation of the six-fold symmetric flower-shaped luminescence in the GaN nanostructures. The formation of this pattern is attributed to strain at early stage of growth and unintentional doping. (iii). The growth of InGaN/GaN multi-quantum well structures and their optical properties for different Si/Mg doping. This project deepens our understanding of GaN nanorods growth mechanism and related optical properties, which will benefit future device applications.

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