Segmented CVD reactor designs enabling spatial control of across-wafer gas phase composition were evaluated for depositing graded films suitable for combinatorial studies. Specifically, two reactor designs were constructed and evaluated with experiments and response surface model (RSM) based analysis to quantify the reactor performance in terms of film thickness uniformity, sensitivity to adjustable reactor operating conditions, range of thickness over which uniformity could be achieved and each reactor's ability to control the thickness gradient across the wafer surface. Design features distinguishing the two reactor systems and their influence on gradient control vs. deposition rate performance are summarized. RSMs relating wafer state properties to process recipes are shown to be effective tools to quantify, qualify and compare different reactor designs. (C) 2007 Published by Elsevier B.V.