An electrically detected magnetic resonance study of performance limiting defects in SiC metal oxide semiconductor field effect transistors

In this study, we utilize electrically detected magnetic resonance (EDMR) techniques and electrical measurements to study defects in SiC based metal oxide semiconductor field effect transistors (MOSFETs). We compare results on a series of SiC MOSFETs prepared with significantly different processing parameters. The EDMR is detected through spin dependent recombination (SDR) in most cases. However, in some devices at a fairly high negative bias, the EDMR likely also involves spin dependent trap-assisted tunneling (SDT) between defects on both sides of the SiC / SiO 2 interface. At least three different defects have been detected in the magnetic resonance measurements. The defects observed include two at the SiC / SiO 2 interface or on the SiC side of the SiC / SiO 2 interface: one is very likely a vacancy center with a distribution which extends into the bulk of the SiC and the other is likely a "dangling bond" defect. A third defect, located on the SiO 2 side of the SiC / SiO 2 interface, has a spectrum very similar to that previously reported for an oxygen deficient silicon coupled to a hydrogen atom. In nearly all cases, we observe a strong dominating single line EDMR spectrum with an isotropic g ≈ 2.0027 . In some samples, this strong central line is accompanied by two pairs of considerably weaker side peaks which we link to hyperfine interactions with nearby Si and C atoms. The pattern is physically reasonable for a silicon vacancy in SiC. We therefore tentatively assign it to a silicon vacancy or silicon vacancy associated defect in the SiC. In one set of devices with very high interface trap density we observe another dominating spectrum with g ∥ = 2.0026 and g ⊥ = 2.0010 with the symmetry axis coincident with the [0001] and nearly the SiC / SiO 2 interface normal. We ascribe this EDMR spectrum to a "dangling bond" defect. A third EDMR spectrum shows up in some devices at a fairly large negative gate bias. The phase of this spectrum is quite consistently opposite to that of the SDR detected EDMR at other biases. Part of this inverted phase spectrum involves two narrow lines which are separated by ≈10.5 G. Since the center responsible for this spectrum is almost certainly in the SiO 2 , it is likely due to the so called 10.4 G doublet center, an unpaired electron residing on an oxygen deficient silicon atom coupled to a hydrogen in SiO 2 . The likely presence of one oxygen deficient silicon defect suggests that other oxygen deficient silicon atom defec