Interaction of low-energy muons with defect profiles in proton-irradiated Si and 4H -SiC

Muon spin rotation $(\ensuremath{\mu}\text{SR})$ with low-energy muons is a powerful nuclear method where electrical and magnetic properties of thin films can be investigated in a depth-resolved manner. Here, we present a study on proton-irradiated Si and 4H-SiC where the formation of the hydrogen-like muonium (Mu) is analyzed as a function of the proton dose. While the Mu formation is strongly suppressed in the highly defective region of the shallow proton stopping profile, the Mu signal quickly recovers for higher muon energies where the muons reach the untreated semiconductor bulk. A lower sensitivity limit of low-energy $\ensuremath{\mu}\text{SR}$ to crystal defects of around ${10}¹⁷$ to ${10}¹⁸\phantom{\rule{0.28em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$ is estimated. Our results demonstrate the high potential of this technique to nondestructively probe near-surface regions without the need for electronic device fabrication and to provide valuable complementary information when investigating defects in semiconductors.