Indium nitride epilayers grown by metalorganic vapor-phase epitaxy have been studied by cathodo luminescence (CL) spectroscopy, scanning tunneling microscopy and scanning tunneling spectroscopy (STS). A broad CL emission peak centered at 0.8 eV was observed at 80 K. This peak was attributed to an excitonic radiative recombination mechanism as its emission intensity exhibited a super-linear dependence on beam current with a power-law exponent of m = 2. A large spatial variation in the CL emission intensity was ascribed to the presence of threading dislocations, which act as nonradiative recombination centers. A surface band gap of similar to1.4 eV was estimated from STS I-V curves. (C) 2004 Elsevier B.V. All rights reserved.