The micro-Raman mapping with a spatial resolution of micrometer has been carried out on hexagonal InN thin films grown by reactive sputtering on GaAs (I 1 1) substrates at 100degreesC under different sputtering pressures. The distributions of correlation lengths in the InN films, which have a close relation with the defect concentration and the crystal quality, have been yielded by combining a special correlation model with a Lorenz function. We have employed the statistical method to analyze the average value and standard deviation of the correlation length in all the InN samples, and find that the one under a sputtering pressure of 10mTorr has the best quality in average, but with the highest nonuniformity. The roles of the grain size fluctuation on the thin film nonuniformity and the InN/GaAs interfaces have been clearly revealed. (C) 2003 Elsevier B.V. All rights reserved.