ENVIRONMENT ABOUT INDIUM IN GA1-XINXN FROM IN AND GA K-EDGE XAFS

GaN doped with various amounts of In can be used to make diodes with c olors from blue to green. In order to determine the effect of the In o n the local nitrogen and gallium environment, we have collected both I n and Ga K-edge XAFS data on films of Ga1-xInxN. The distribution of I n in the GaN matrix was found to be random both by plotting the amplit ude of the In-Ga/In peak vs. x and from more detailed fits, although s mall clusters of three or fewer In atoms cannot be ruled out. In-In an d In-Ga atom pairs are of comparable bond length, increasing approxima tely linearly with concentration x. These atom-pair distances are betw een the Ga-Ga distance in GaN (3.18 Angstrom) and the In-In distance i n InN (3.52 Angstrom), Ga edge data is consistent with this distributi on, but further distortions make detailed fits more difficult.