X-ray studies of defects and thermal vibrations in an organometallic vapor phase epitaxy grown GaN thin film

A semiconducting GaN thin film with the 001 plane parallel to the surface grown by organometallic vapor phase epitaxy method on (110) sapphire was studied using x-ray diffraction. The line profiles of the GaN thin film along the [001] direction can be quantitatively reproduced assuming a strained lattice at the interface. The deformation and growth faults were determined to be equal and each is 0.2%. Least-squares refinement on 42 independent peaks, after correcting for the first-order thermal diffuse scattering, gives the values of the Debye-Waller factor for Ga (B-11=0.28, B-33=0.26) and N (B-11=0.38, B-33=0.26) atoms. The wurtzite positional parameter u for this GaN thin film was found to be 0.3730, 1% smaller than that in a strain-free single crystal (u=0.377), most probably resulting from the strain effects. (C) 1997 American Institute of Physics.