Remote plasma asisted MOCVD growth of GaN on 4H-SiC: growth mode characterization exploiting ellipsometry

GaN is grown on Si-face 4H-SiC(0001) substrates using remote plasma-assisted metalorganic chemical vapour deposition (RP-MOCVD). The pre-dissociation of nitrogen by the remote plasma is used for lowering the deposition temperature to approximately 700 degrees C. Remote plasma processing is also used for SiC surface pre-treatments including a low-temperature atomic hydrogen cleaning ( by remote H(2) plasma) and nitridation ( by remote N(2) plasma). Furthermore, in situ spectroscopic ellipsometry is used for monitoring in real time all the steps of substrate pre-treatments and the heteroepitaxial growth of GaN on SiC. Our characterization emphasis is on understanding the nucleation mechanism and the GaN growth mode, which depend on the SiC surface preparation.