Comparison of near-interface traps in Al_(2)O_(3)/4H-SiC and Al_(2)O_(3)/SiO_(2)/4H-SiC structures

摘要

Aluminum oxide (Al_(2)O_(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_(2)O_(3) dielectric exhibit a nearly trap-free region close to E_(c). For the Al_(2)O_(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_(2)O_(3) as the gate dielectric layer in future high performance devices.