Growth and characterization of AlxGa1-xN lateral polarity structures

Abstract

AlGaN lateral polarity structures (LPS) with varying Al composition, have been fabricated by metalorganic chemical vapour deposition on LPS templates containing μm size domains. III-metal and N-polar AlGaN domains have been grown on LT-AlN and c-sapphire domains, respectively. LPS characterization by SEM and AFM reveals two major effects when the Al composition has been varied: (a) A high Al content leads to columnar growth within N-polar domains and (b) a height difference between the polar domains can be observed for low Al compositions towards III-polarity. The surface quality of the III-polar domains is not effected by the Al composition. The surface roughness of N-polar domains decreases for lower Al compositions. The high periodicity of the polar domains and the high quality of the boundary between domains suggest a high potential of AlGaN LPS to be used as lateral wave guides for quasi phase matching.