Low threading dislocation density aluminum nitride on silicon carbide through the use of reduced temperature interlayers

Publication date: 1 February 2018
Source:Journal of Crystal Growth, Volume 483
Author(s): Humberto M. Foronda, Feng Wu, Christian Zollner, Muhammad Esmed Alif, Burhan Saifaddin, Abdullah Almogbel, Michael Iza, Shuji Nakamura, Steven P. DenBaars, James S. Speck
In this work, reduced threading dislocation density AlN on (0001) 6H-SiC was realized through the use of reduced temperature AlN interlayers in the metalorganic chemical vapor deposition growth. We explored the dependence of the interlayer growth temperature on the AlN crystal quality, defect density, and surface morphology. The crystal quality was characterized using omega rocking curve scans and the threading dislocation density was determined by plan view transmission electron microscopy. The growth resulted in a threading dislocation density of 7 × 10⁸ cm⁻² indicating a significant reduction in the defect density of AlN in comparison to direct growth of AlN on SiC (∼10¹⁰ cm⁻²). Atomic force microscopy images demonstrated a clear step-terrace morphology that is consistent with step flow growth at high temperature. Reducing the interlayer growth temperature increased the TD inclination and thus enhanced TD-TD interactions. The TDD was decreased via fusion and annihilation reactions.