Departmental Seminar

Epitaxial growth of III-V compound semiconductors on two dimensional layered materials

Ms Aswani Gopakumar
Australian National University

Direct band gap semiconductor materials such as GaAs, InAs and InP are the materials of choice in many optoelectronic and electronic applications. These materials are synthesized by conventional epitaxial techniques that use thermal and lattice matched substrates for growing the layers or nanostructures.

This epitaxial technique makes use of the unoccupied bonds on the surface of a bulk crystalline material substrate. In 1984, Koma et al. demonstrated a noncovalent unconventional epitaxy driven by van der Waals forces which was called, van der Waals epitaxy. This epitaxy uses a 2D material template such as graphene or mica. The lack of surface dangling bonds greatly relaxes the requirement of lattice mismatch between the grown layer and substrate, thus providing an ideal platform to grow single crystalline materials with reduced defects.

Furthermore, the weak van der Waals bonding allows the grown layer to be easily peeled off the substrate and fabricated into flexible devices. With the growing demand for flexible inorganic device architectures for internet-of-things, photovoltaics and sensor applications, van der Waals epitaxy paves the way for defect free, large area and cost-effective means for epitaxial growth.  

In this talk, I will explore the growth of GaAs nanowires on synthetic mica substrate using metal organic chemical vapour deposition technique, in particular how to achieve improved vertical yield and excellent crystal quality. Optical and structural characterization of nanowires thus grown will be discussed, Next, the growth of InAs nanowires on various 2D templates and how the crystal phase of the nanowires is affected by the choice of template will be discussed. I will then briefly discuss my future plans of growing III-V semiconductors on mica/Ge template and various III-V nanostructures on mica by selective area epitaxy. 

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