Published in J. Vac. Sci. Technol. B 21 1812 (2003).

Plasma-assisted molecular beam epitaxy of GaN on porous SiC substrates with varying porosity

Ashutosh Sagar (a), C. D. Lee (a), R. M. Feenstra (a), C. K. Inoki (b) and T. S. Kuan (b)
(b) Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213
(b) Department of Physics, University at Albany, SUNY, Albany, NY 12222


We have grown GaN on porous SiC substrates and studied the effect of substrate porosity on the overgrown film quality in terms of defect structure and density and film strain. The growth was performed by plasma-assisted molecular beam epitaxy (PAMBE). The GaN films were characterized by x-ray, transmission electron microscopy (TEM) and wafer curvature measurements by surface profilometry. TEM images show that the GaN film grown on porous substrates contains open tubes and a low dislocation density in regions between tubes. We discuss various growth mechanisms that can lead to these defect features in the GaN film. However, we do not find any overall improvement in the x-ray rocking curve FWHM of the GaN films grown on porous substrates compared to those on nonporous substrates. It was found that the GaN films grown on porous SiC were significantly more strain relaxed compared to those grown on nonporous substrate. We propose various mechanisms that can lead to the reduction in strain in GaN films grown on porous substrates and compare the data with finite element analysis (FEA) simulations of such a system.

Click here for preprint of paper, in pdf format

Return to Home Page of Feenstra group