Speaker
Description
III-nitride nanowire arrays driven by diffusion-induced process of plasma-assisted molecular beam epitaxy (PA-MBE) has provided straight and axially-grown one-dimensional (1-D) nanostructures for optoelectronic device applications. As compared with the planar layer platform, nanowires-based epitaxial growth technology has distinct advantages of dislocation-free nature combined with reduced lattice strain and smaller Stark effect in quantum-confined double-heterostructures, resulting in a lower piezoelectric polarization field.
In this talk, we focus on the basic growth kinetics and the epi-structure design of PA-MBE grown GaN-nanowires-based p-i-n structures, for the realization of light-emitting diodes (LEDs). Firstly, GaN seeds are nucleated and self-planarized GaN nanowires are successfully grown by a self-assembled growth mechanism on the Ti-coated amorphous fused-silica and Si substrates. After introducing the Ti pre-orienting layer, the electrical conductivity was found to increase, with reduced sheet resistance and improved interface. As a second part, GaN-nanowires-based p-i-n structures were grown using selective area growth (SAG) on a GaN/sapphire template, by using the Ti layer as a mask. The SAG method provided better controlled nucleation and elongation only in the mask-window positions and thus, high external quantum efficiency was achieved. These achievements can open a new way for III-nitride semiconductors on various material platforms for optoelectronic device applications.
