Photoelectron spectra of Al dopants in 4H-SiC

We report on a photoelectron spectroscopy study of Al-dopants in 4H-SiC epitaxial layers. For silicon carbide (SiC) samples with an Al concentration of 1020 cm-3 we have been able to detect the Al2p photoemission signal. The Al2p signal is recorded through the oxide layer with a thickness of about 0.4 nm. We identify the emission signal of dopants and of small clusters. The latter become oxidized by diffusion of oxygen through the native oxide