ALD Deposited Al_2O_3 Films on 6H-SiC(0001) after Annealing in Hydrogen Atmosphere

摘要

Atomic Layer Deposited Al_2O_3 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 Si~(4+) as a new component besides Si~0 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 SiO_2 layer and a rougher interfacial layer containing more Si~+ and Si~(4+) which could be responsible for the strong increase of D_(it) just below the conduction band edge.