Indium nitride is not yet fully characterized or understood, despite being the endpoint of the commercially valuable InxGa1-xN system. There is still considerable controversy over such fundamental issues as the band gap, with recent evidence suggesting that it may be as low as 0.6eV. We have deposited InN films on a range of substrates, including silica glass, (0 0 0 1) sapphire and (1 1 1) YSZ, using plasma assisted molecular beam epitaxy (PAMBE). These films were characterized, during growth and ex situ, and a strong luminescence feature between 0.7 and 0.8eV was found in all films, regardless of quality. (C) 2004 Elsevier B.V. All rights reserved.