Wurtzite GaN films have been grown on (001) Si substrates using γ-Al2O3 as an intermediate layer by low pressure (∼76 Torr) metalorganic chemical vapor deposition. Reflection high energy electron diffraction and double crystal x-ray diffraction measurements revealed that the thin γ-Al2O3 layer of “compliant” character was an effective intermediate layer for the GaN film grown epitaxially on Si. The narrowest linewidth of the x-ray rocking curve for (0002) diffraction of the 1.3 μm GaN sample was 54 arcmin. The orientation relationship of GaN/γ-Al2O3/Si was (0001) GaN∥(001) γ-Al2O3∥(001) Si, [11–20] GaN∥ γ-Al2O3∥ Si. The photoluminescence measurement for GaN at room temperature exhibited a near band-edge peak of 365 nm (3.4 eV). © 1998 American Institute of Physics.