Dissociation of deuterium-defect complexes in ion-implanted epitaxial 4H-SiC

Epitaxial layers of low doped 4H-SiC are implanted with 20 keV 2H+ ions to a dose of 1 x 1015 cm-2. The samples are subsequently annealed at temperatures ranging from 1040 to 1135 C. Secondary ion mass spectrometry is used to obtain the concentration versus depth profiles of the atomic deuterium in the samples. It is found that the concentration of implanted deuterium decreases rapidly in the samples as a function of anneal time. The experimental data are explained by a model where the deuterium migrates rapidly and becomes trapped and de-trapped at implantation-induced defects which exhibit a slightly shallower depth distribution than the implanted deuterium ions. Computer simulations using this model, in which the damage profile is taken from Monte Carlo simulations and the surface is treated as a perfect sink for the diffusing deuterium atoms, are performed with good results compared to the experimental data. The complexes are tentatively identified as carbon-deuterium at a Si-vacancy and a dissociation energy (ED) of approximately 4.9 eV is extracted for the deuterium-vacancy complexes