A comparative study is presented of the effect of reactant sequencing during the metalorganic vapor phase epitaxy of GaAs1-yBiy on epilayer composition and structural properties. The simultaneous introduction of precursors was compared with a pulsed or alternating reactant flow. Pulsed growth resulted in a more controlled incorporation of Bi into the GaAs epitaxial layers and led to a more well-defined superlattice structure as determined by X-ray diffraction. The effect of growth temperature (370-420 degrees C) and precursors flow rate on the film properties and Bi incorporation was determined. While growth rate of GaAs decreased with decreasing growth temperature, the GaAs1-yBiy growth rate was almost temperature insensitive over this investigated temperature range. The catalytic effect of Bi metal or the trimethyl bismuth reactant on the decomposition and incorporation of Ga is considered to rationalize this observed behavior. The specific choice of reactant flow and temperature can strongly influence the material properties of the GaAs1-yBiy films. These observations suggest the possibility of the growth of GaAs1-yBiy hetero-structures at the temperatures below what was assumed to be the lowest possible temperature for the growth of GaAs. (C) 2013 Elsevier B.V. All rights reserved.