Atomic-scale origins of bias-temperature instabilities in SiC–SiO2 structures

We find that atomic-scale mechanisms for bias-temperature instabilities (BTIs) in SiC/SiO2 structures can differ significantly from those in Si/SiO2 structures. The measured effective-activation energies for BTI in 4H-SiC metal-oxide-semiconductor capacitors, 0.23±0.02 eV for p-type and 0.12±0.02 eV for n-type, are essentially identical to the respective dopant ionization energies, which are much larger than in Si. This suggests a key role for carrier release from deep dopants for BTI in SiC. In addition, asymmetric degradation is observed under switched-bias stress in p-type and n-type SiC, as a result of the reconfiguration of O vacancies in SiO2 layer after hole capture.