Tert-butylarsine, a less toxic and dangerous compound than arsine (AsH3), is investigated as a precursor for metalorganic vapor phase epitaxy. We have performed a comparative study on two InGaAs/InP multi-quantum well samples sharing a nominally identical structure and composition but grown with these two different arsenic sources. X-ray diffraction and optical spectroscopy (reflectivity and photoluminescence) show high material quality for both sets of samples. In particular, the use of tert-butylarsine promotes flatter interfaces characterized by a compositional grading of a few monolayers. (C) 2002 Elsevier Science B.V. All rights reserved.