Determination of parameters for channeling of protons in SiC polytype crystals in the backscattering geometry

Energy spectra of protons channeling along the (0001) axis of several SiC polytype crystals (namely 4H, 6H, 15R, 21R) in the energy region E-p = 1.7-2.5 MeV, in the backscattering geometry, were taken and analyzed. Computer simulations based on the assumption that the dechanneling of protons follows an exponential law are in very good agreement with the measured spectra. The obtained results for the two crucial channeling parameters, gimel, the mean channeling distance, and, alpha, the ratio of the stopping powers in the aligned and random mode are compared for the different structures and an attempt is made to explain the occurring similarities as well as the differences, in order to evaluate the use of SiC polytypes as substrates in implantations and thin film depositions. An attempt is also made to correlate the results from the present work to the ones obtained in the past for simpler crystallographic structures, namely Si(100) and Si(111), as well as more complex ones, such as SiO2 (c-axis). (C) 2001 Elsevier Science B.V. All rights reserved