Al–O–Al defect complexes as possible candidates for channel electron mobility reducing trapping centers in 4H-SiC metal–oxide–semiconductor field-effect transistors

Abstract

The deep-level drain current transient spectroscopy (Id-DLTS) measurements of Al -doped SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) strongly suggest that the reduction in the channel mobility at low temperatures is related to a shallow trap detectable at 70 K. Using the Shockley-Reed-Hall (SRH) theory, the level of this trap has been extracted to be around 0.15 eV below the conduction band minimum of SiC. Density functional theory (DFT) calculations of Al_Si N_C Al_Si and Al_Si O_C Al_Si defect complexes have found one configuration of the Al_Si O_C Al_Si complex, which has a charge transition level within the SRH extracted trap level range. Therefore, we suggest that these Al_Si O_C Al_Si defects are likely candidates for traps responsible for the channel mobility reduction.