ALD Deposited Al2O3 Films on 6H-SiC(0001) after Annealing in Hydrogen Atmosphere

Atomic Layer Deposited Al2O3 films on hydrogen-terminated 6H-SiC(0001) were annealed in hydrogen atmosphere and characterized by admittance spectroscopy measurement and photoelectron spectroscopy (PES). The resultant density of interface trap (D(it)) from admittance spectroscopy measurement is reduced near mid gap, but increases strongly towards the conduction band edge. Systematic PES measurements show that hydrogen annealing introduces Si4+ as a new component besides SiDG and Si+. Using different electron escape depths for photon electrons, depth profiling of Si in its different oxidation states was performed. The result indicates the formation of a top SiO2 layer and a rougher interfacial layer containing more Si+ and Si4+ which could be responsible for the strong increase of D1 just below the conduction band edge.