High index contrast InGaAsP/InP gratings are useful in the design of next generation photonic integrated circuits. Here, we investigate the process conditions used in the formation of such gratings. We find that the reactive ion etch conditions have a strong influence on the radiative efficiency in the grating region. We also show that the use of a combination of TBP and TBA in the heat-up phase of growth results in a reduction of the group-V exchange in the grating region, thereby increasing the radiative efficiency, while not adversely affecting non-grating regions. (C) 2004 Elsevier B.V. All rights reserved.