Facet analysis of truncated pyramid semi-polar GaN grown on Si(100) with rare-earth oxide interlayer

Abstract

After epitaxial growth of GaN on Si(100) substrates using an Er2O3 interlayer, two dominant growth orientations can be observed: semi-polar (101¯3) as well as non-polar (112¯0). Epilayers with the (101¯3) orientation lead to the formation of truncated pyramids, which were studied in detail by high-resolution X-ray diffraction, photoluminescence, and scanning electron microscopy (SEM). Depending on the GaN growth orientation and in-plane relation to the Er2O3 interlayer, lattice mismatches in the growth plane were calculated. In order to understand the formation of truncated pyramids, a method for facet identification from SEM images under different tilt angles was developed. This method was used to reconstruct truncated pyramids from our experiments. These were then compared with calculations of the corresponding kinetic Wulff construction, to explain the preferential growth of (101¯3) GaN.