Enhanced oxidation of ion-damaged 6H-SiC

Thermal oxidation of the Si face of 6H-SiC was investigated in single-cryst al and ion-implanted material. The samples were irradiated with Si and Kr i ons at different fluences and the damage produced was studied with Rutherfo rd back scattering in the channelling configuration. The oxidation was perf ormed at a temperature of 1150 degrees C for times ranging from 1 to 10 h. The oxide thickness was measured by Rutherford back-scattering and ellipsom etric measurements. It was found that the oxidation rate in ion-damaged 6H- SiC is larger than in unimplanted samples. The oxide thickness increases wi th increasing ion fluence and it saturates at a fluence corresponding to co mplete amorphization of the surface layer. The enhanced oxidation is ascrib ed to breakdown of the strong covalent Si-C bonds induced by ion irradiatio n, resulting in an increase in the chemical reactivity. Capacitance-voltage measurements, performed in order to characterize the oxide layer, show the presence of a large amount of charge in the oxide grown on damaged SiC sam ples.