Fluence, flux, and implantation temperature dependence of ion-implantation-induced defect production in 4H-SiC

• Vacancy-type defect production in Al- and Si-implanted 4H-SiC has been studied as a function of ion fluence, ion flux, and implantation temperature in the projected ion range region by positron annihilation spectroscopy and Rutherford backscattering techniques. Ion channeling measurements show that the concentration of displaced silicon atoms increases rapidly with increasing ion fluence. In the ion fluence interval of 10(13)-10(14) cm(-2) the positron annihilation parameters are roughly constant at a defect level tentatively associated with the divacancy VCVSi. Above the ion fluence of 10(14) cm(-2) larger vacancy clusters are formed. For implantations as a function of ion flux (cm(-2) s(-1)), ion channeling and positron annihilation measurements behave similarly, i.e., indicating increasing damage in the projected range region with increasing ion flux. However, for samples implanted at different temperatures the positron annihilation parameter S shows a clear minimum at approximately 100 degreesC, whereas the normalized backscattering yield decrease continuously with increasing implantation temperature. This is explained by the formation of larger vacancy clusters when the implantation temperature is increased.

Nyckelord

monoenergetic positron beams

vacancy-type defects

damage evolution

silicon-carbide

self-diffusion

aluminum ions

al

annihilation

si

distributions

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