An experimental study has been made of correlations between electrical and optical properties for OMVPE InN grown on sapphire substrate. Carrier concentration for a grown film is found to decrease with increasing growth temperature and shows the lowest value 5.8 x 10(18) cm(-3) at 600degreesC. A strong photoluminescence (PL) with a peak energy of 0.7-0.8 eV is observed at room temperature. As a general trend, PL peak energy and optical absorption edge increase with increasing carrier concentration (Burstein-Moss shift). For relatively thick films with large grains, grown at a relatively high temperature, a discrepancy is found between carrier concentration obtained by Hall measurement and PL data. Such samples show a PL spectrum with a lower peak energy and a smaller FWHM in spite of a higher carrier concentration. Although Hall measurement gives a carrier concentration as high as 2.3 x 10(19) cm(-3) for the sample grown at 620degreesC, this sample should have a much lower carrier concentration because the PL peak energy is lower than that for the sample with the lowest carrier concentration 5.8 x 10(18) cm(-3). These results show that the optimum growth temperature is higher than 600degreesC determined from the electrical characterisation. (C) 2003 Elsevier B.V. All rights reserved.