Defects reduction in a-plane AlGaN epi-layers grown on r-plane sapphire substrates by metal organic chemical vapor deposition

Abstract

Abstract Nonpolar a -plane AlGaN epi-layers were grown on a semi-polar r -plane sapphire substrate with an innovative two-way pulsed-flows metal organic chemical vapor deposition growth technology. A root-mean-square value of 1.79 nm was achieved, and the relative light transmittance of the a -plane AlGaN epi-layer was enhanced by 36.9%. These results reveal that the innovative growth method is able to improve the surface morphology and reduce the defect density in nonpolar a -plane Al x Ga 1– x N epi-layers, particularly those with an Al composition greater than 0.5, which are key materials for the fabrication of nonpolar AlGaN-based high light emission efficiency deep-ultraviolet light-emitting diodes.