In situ etching of InP with tertiarybutylchloride under metalorganic vapor phase epitaxy conditions was investigated with respect to etching profiles, surface morphology. and lateral etching uniformity. Etching of mesa structures resulted in positively sloped sidewalls independent of crystal orientation and etching parameters. Depending on specific etching temperature regimes. excellent surface morphology could be achieved with the addition of PH3, or TBP, or even without the presence of any group(V) species, However, strong generation of etch pits was encountered with materials containing high dislocation densities. Preliminary measurements suggest the lateral etched rate uniformity to be very sensitive to the thermal conditions in the reactor owing to the kinetic nature of the etching process. (C) 2002 Elsevier Science B.V. All rights reserved.