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 (Al2O3) has been grown by atomic layer deposition on n-type4H-SiC with and without a thin silicon dioxide (SiO2) intermediate layer. Bymeans of Capacitance Voltage and Thermal Dielectric Relaxation Currentmeasurements, the interface properties have been investigated. Whereas for thesamples with an interfacial SiO2 layer the highest near-interface trap densityis found at 0.3 eV below the conduction band edge, Ec, the samples with onlythe Al2O3 dielectric exhibit a nearly trap free region close to Ec. For theAl2O3/SiC interface, the highest trap density appears between 0.4 to 0.6 eVbelow Ec. The results indicate the possibility for SiC-based MOSFETs with Al2O3as the gate dielectric layer in future high performance devices.