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Benoît Amstatt

Growth of m-plane non-polar GaN/AlN heterostructures on m-plane 6H-SiC

Published on 27 March 2008

Thesis presented March 27, 2008

This work reports on the growth and the structural and optical properties of non-polar m-plane GaN/AlN heterostructures deposited on m-plane 6H-SiC by Plasma Assisted Molecular Beam Epitaxy.
We first studied AlN and GaN thick layers. The optimal growth conditions were achieved in metal-rich conditions. They both exhibit anisotropic surface morphology: stripped for AlN and slatted for GaN.
Next, we studied the growth of GaN/AlN heterostructures. GaN quantum wells are obtained in N-rich conditions whereas GaN quantum wires or quantum dots are formed in Ga rich conditions by Stranski-Krastanow growth mode. The shape of these GaN nanostructures is depending on the strain state of the AlN buffer layer. Optical studies revealed a strong reduction of the internal electric field in m-plane GaN/AlN heterostructures.
Finally, we focused on the shape evolution of wires and dots with the amount of GaN deposited. We demonstrated the existence of a dots to wires transition. It takes place above a critical size that can be controlled by the amount of GaN deposited or by the growth of superlattices.

Molecular beam epitaxy, non-polar, m-plane, quantum dots, quantum wires, anisotropy

On-line thesis.