Hydrogen–boron complex formation and dissociation in 4H–silicon carbide

The diffusion of deuterium (2H) in p-type 4H–silicon carbide (SiC) has been studied in detail by secondary ion mass spectrometry. An effective capture radius for the formation of 2H–B complexes at 460 °C is determined to RHB=(21±4) Å. This value is in good agreement with that expected for a coulomb force-assisted trapping mechanism. At higher temperatures, the 2H diffusion follows Fick’s law with a constant effective diffusivity from which the complex dissociation frequencies νHB are determined. The frequencies exhibit an Arrhenius temperature dependence over the three orders of magnitude covered by the extracted νHB. The complex dissociation energy is determined to EdHB=(2.51±0.04) eV which is 0.9 eV larger than the corresponding value for the 2H–Al complex, suggesting that the atomic configurations for the two complexes are significantly different. The extracted dissociation attempt frequency, ν0HB=(1.2±0.7)×1013 s−1 is very close to the characteristic oscillation frequency of the SiC lattice, νlatticeSiC=1.6×1013 s−1. In addition, 2H diffusion in an epitaxial Al multilayer structure demonstrates the influence of internal electric fields on the 2H diffusion in p-type SiC.