Heteroepitaxial growth of GaN on Si(l 1 1) substrate was investigated by atmospheric pressure organometallic vapor-phase epitaxy. High-quality GaN layers on Si were deposited using an epitaxially grown intermediate layer of gamma-Al2O3. The orientation relationship was found to be GaN(0001)/gamma-Al2O3(111)/Si(111) and GaN[11 (2) over bar1] parallel to gamma-Al2O3[(1) over bar 10]parallel toSi[(1) over bar 10]. GaN layers with (0002) rocking curve line width of 1000arcsec have been obtained. (C) 2002 Elsevier Science B.V. All rights reserved.