Environment about indium in G _1-xIn _xN from in Ga K-edge XAFS

GaN doped with various amounts of In can be used to make diodes with colors from blue to green. In order to determine the effect of the In on the local nitrogen and gallium environment, we have collected both In and Ga K-edge XAFS data on films of Ga _1-xIn _xN. The distribution of In in the GaN matrix was found to be random both by plotting the amplitude of the In-Ga/In peak vs. x and from more detailed fits, although small clusters of three or fewer In atoms cannot be ruled out. In-In and In-Ga atom pairs are of comparable bond length, increasing approximately linearly with concentration x. These atom-pair distances are between the Ga-Ga distance in GaN (3.18 Å) and the In-In distance in InN (3.52 Å). Ga edge data is consistent with this distribution, but further distortions make detailed fits more difficult.