Effect of Nuclear Scattering Damage at SiO_2/SiC and Al_2O_3/SiC Interfaces - A Radiation Hardness Study of Dielectrics

摘要

The radiation hardness of Al_2O_3 as a dielectric for SiC surface passivation is studied and compared to SiO_2 for potential application in radiation hard SiC devices. SiO_2 is deposited on 4H-SiC by PECVD and post annealed in N_2O, whereas Al_2O_3 is deposited by atomic layer deposition (ALD). The oxides are bombarded with Ar ions in an energy range to produce maximum damage near the oxide/SiC interface. Metal-insulator-semiconductor structures are prepared and their dielectric characteristics are analyzed using capacitance-voltage measurements. Additionally, the effect of the interface damage on surface recombination is studied using the optical free carrier absorption method for the same samples. The results indicate that the SiO_2/SiC interface is significantly affected at 1×10~(11) cm~(-2) fluence of Ar ions, however, the dielectric properties of Al_2O_3/SiC interface remain unaffected even for ten times higher fluences. Similar observations are made for the surface recombination measurements.