Comparison of near-interface traps in Al_2O_3/4H-SiC and Al_2O_3/SiO_2/4H-SiC structures

摘要

Aluminum oxide (Al_2O_3) has been grown by atomic layer deposition on n-type 4H-SiC with and without a thin silicon dioxide (SiO_2) intermediate layer. By means of capacitance-voltage and thermal dielectric relaxation current measurements, the interface properties have been investigated. Whereas for the samples with an interfacial SiO_2 layer the highest near-interface trap density is found at 0.3 eV below the conduction band edge E_c, the samples with only the Al_2O_3 dielectric exhibit a nearly trap-free region close to E_c. For the Al_2O_3/SiC interface, the highest trap density appears between 0.4 and 0.6 eV below E_c. The results indicate the possibility for SiC-based metal-oxide-semiconductor field-effect transistors with Al_2O_3 as the gate dielectric layer in future high performance devices.