Suppression of carbon desorption from 4H-SiC by irradiating a remote nitrogen plasma at a low temperature

We remotely irradiated a nitrogen plasma onto the carbon-side surface of 4H-SiC at a low temperature, and examined the effect of sample cooling on the characteristics of the nitride layer. An improved nitride layer, which had higher concentrations of carbon and silicon and a lower concentration of oxygen, was formed in the region at depths of more than 0.6-0.9nm from the top surface. The depth of the fragile nitride layer in the top region, where no improved characteristics of the nitride layer were observed, became smaller with sample cooling. In addition, on the basis of the experimental results, we discussed the difference in the activation energy of the nitriding reaction of 4H-SiC supported by atomic nitrogen and molecular nitrogen in the metastable A(3)Sigma(+)(U) state

Nitriding of 4H-SiC by irradiation of fourth harmonics of Nd:YAG laser pulses in liquid nitrogen

This study presents surface nitriding of 4H-SiC by the irradiation of the fourth harmonics of Nd:YAG laser pulses in liquid nitrogen. A nitride layer with a depth of 1 mu m is formed on the irradiated area. The irradiated area has a bumpy morphology. On the other hand, we also find a nitride layer with a smooth surface morphology in the outside of the irradiated area. The concentration of nitrogen is dependent on the laser fluence, and is 1-5%. The diffusion coefficient of nitrogen, which is deduced from the depth profile of the nitrogen number density, is much greater than the diffusion coefficient in solid SiC, suggesting the transport of nitrogen in melted SiC. Considering the fact that SiC does not have a melted state at the atmospheric pressure, it is revealed by the present work that the melted SiC is realized transiently with the help of the high pressure driven by the laser irradiation