Epitaxial lateral overgrowth of GaN on 4 inch Si(111) by MOVPE

摘要

Epitaxial Lateral Overgrowth (ELOG) of GaN on 4 inch sili-con(111) substrates by MOVPE was investigated in this study. ELOG was performed on a GaN template with a couple of AlGaN intermediate layers (IL) on an A1N nucleation layer. The AlGaN ILs supply compressive stress to the top GaN template and thereafter to the ELOG layer. Consequently, layer cracking is minimized. Two masks were used in this work: a 2 inch wagon wheel mask and a 4 inch maskrnwith parallel stripes of various filling factors and periods. The filling factor is varied from 0.33 to 0.7. The periodic spacing is in the range of 6 μm to 10 μm. Temperature, V/III ratio, pressure and stripe orientation were optimized to achieve fastest lateral growth rate. The highest lateral to vertical ratio can be more than 4. A fully coalesced layer within the critical thickness for a crack-free layer was achieved on 4 inch silicon substrates.