Regularization methods for the extraction of depth profiles from simulated ARXPS data derived from overlayer/substrate models

Starting from posited input depth profiles of silicon oxide on silicon, 100 sets of noisy simulated ARXPS data were created for each oxide layer thickness of 3, 6, 9, 12, 15, 18, 21, 24 and 27 angstrom. Oxygen depth profiles were then recovered from the noisy simulated data using regularized inversion methods, including maximum entropy and Tikhonov regularization. Three regularization parameters were used: one determined by the S-curve method, one determined by the L-curve method and a third corresponding to the closest correspondence between the input and extracted profiles. The various regularization schemes evaluated were ranked with respect to their ability to reproduce the input profile. (C) 2011 Elsevier B.V. All rights reserved.