Diffusion of the Carbon Vacancy in a-Cut and c-Cut n-Type 4H-SiС
The diffusion of the carbon vacancy (VC) in n-type 4H-SiC has been studied using Deep Level Transient Spectroscopy (DLTS). Samples grown along two different crystallographic planes, (0001) or c-cut and (11-20) or a-cut, have been utilized. The samples were implanted with 4.0 MeV C ions to generate VC’s and subsequently annealed at temperatures between 200 and 1500 °C. Following each annealing stage, concentration versus depth profiles of the VC were obtained. The VC is essentially immobile in both the c-cut and a-cut samples up to at least 1200 °C. The 1400 °C annealing stage, however, resulted in considerable migration, predominantly along the a-direction. Using half the difference in the Full Width at Half Maximum (FWHM) of the initial and diffused concentration profiles as a measure of the diffusion length, we deduced the diffusivity of the VC at 1400 °C to be approximately (3.8±1.1)×10-14 cm2/s along the c-axis and (4.1±1.2)×10-13 cm2/s along the a-axis, indicating a substantial anisotropy for the VC diffusion in 4H-SiC.
Robert Stahlbush, Philip Neudeck, Anup Bhalla, Robert P. Devaty, Michael Dudley and Aivars Lelis
M. E. Bathen et al., "Diffusion of the Carbon Vacancy in a-Cut and c-Cut n-Type 4H-SiС", Materials Science Forum, Vol. 924, pp. 200-203, 2018