Defect Profiling of Oxide-Semiconductor Interfaces Using Low-Energy Muons

Depth-Resolved Study of the SiO₂- SiC Interface Using Low-Energy Muon Spin Rotation Spectroscopy

“…The 1300x and 1300Ar1300 samples exhibit similar behavior while the contrast is stark to the case after NO annealing. For the NO annealed samples almost no Mu 0 precession is observed, indicating that the fraction of the implanted muons forming Mu 0 quickly transforms to Mu − or quickly depolarizes due to the interaction with free charge carriers [3,30]. A sharp reduction in phase was recorded, see Fig.…”

“…Typically, in thermally grown SiO 2 , Mu 0 formation is supported due to high structural order and therefore a small diamagnetic asymmetry (A D ) signal is observed. However, close to the interface a high concentration of defects or structural disorder is expected which leads to an increase in A D at the expense of the paramagnetic Mu 0 [30]. In 4H-SiC, at 10 K, a freeze out of carriers is expected.…”

“…The bulk level shown in Fig. 3 and 4 a) as reference is taken from the µSR data of an unprocessed, low doped n-type 4H-SiC sample [30]. The POA in NO environment has a substantial impact on the diamagnetic signal.…”

“…An important conclusion that can be drawn by looking at the A D value for the NO and Ar annealed samples is that the increase in the A D signal for NO annealed samples cannot be attributed to the temperature alone and NO has a pivotal role to play at the oxide-semiconductor interface. The paramagnetic Mu 0 has a single precession frequency in SiO 2 (ω SiO2 Mu ) while it splits into two lines (ω SiCa Mu , ω SiC b Mu ) due to an anisotropic hyperfine coupling in 4H-SiC [30]. Due to the difference in the precession frequencies, the muonium states in SiO 2 and SiC can be distinguished, enabling identification of the interface location.…”