This paper reports the electrical and optical properties of InN films grown by conventional metalorganic vapor-phase epitaxy (MOVPE) and laser-assisted MOVPE (LA-MOVPE) using an ArF excimer laser. On the basis of these properties, the most plausible donor in MOVPE InN is discussed. The carrier concentration for MOVPE InN decreases with increasing NH3/TMI molar ratio even when growth proceeds under a N-rich environment, suggesting that either a substitutional impurity at N sites or a N-vacancy related defect serves as the donor in MOVPE InN. The LA-MOVPE samples reveal that oxygen can be easily incorporated into InN. It is concluded that the most probable donor candidate for MOVPE InN is oxygen. Incorporation of oxygen into InN decreases with increasing growth pressure and temperature. The reduced oxygen level for InN grown at high temperature is presumably due to the volatility of In-O compounds. The best data obtained for MOVPE InN are a carrier concentration of 4.7 x 10(18) cm(-3) and a mobility of I 100 cm(2)/Vs. InN film quality can be further improved by reducing the amount of oxygen being incorporated into the growing InN. (c) 2005 Elsevier B.V. All rights reserved.