Optical characterization of 4H-SiC by far ultraviolet spectroscopic ellipsometry

We have developed a far UV spectroscopic ellipsometer system working up to 9 eV, and applied it to the characterization of three 4H-SiC samples with d ifferent surface conditions [i.e., as-received and chemical mechanical proc essing (CMP) processed 4H-SiC bulk substrates and a 4H-SiC epi sample]. Pse udodielectric functions epsilon (1) and epsilon (2) clearly demonstrate the excellent surface sensitivity of the far UV ellipsometry system as it dist inguishes the improvements provided by CMP process. Simulation results of e llipsometer data indicate the existence of a damaged subsurface layer in th e as-received 4H-SiC bulk substrate. The investigation of sample surfaces u sing atomic force microscopy confirms the results of ellipsometry measureme nts. (C) 2001 American Institute of Physics.