Correlation of recombination dynamics with structural defects in 4H–SiC epitaxial wafers revealed by TRPL

Abstract

This work demonstrates that deep-UV (266 nm) laser-excited time-resolved photoluminescence (TRPL), combined with controlled surface passivation, provides a sensitive probe for carrier recombination in commercial 4H–SiC epitaxial wafers. Dry oxidation followed by NO/N2 annealing, with optional high-temperature H2 etching prior to oxidation, reduces the front-surface recombination velocity (S1) to ∼2.5 × 103 cm/s, enabling clearer resolution of recombination processes within the epilayer and at the epilayer/substrate interface. Correlation with wafer-scale defect mapping reveals that S1 is linked to pit-like surface defects, whereas variations in the epilayer lifetime (τepi) and interface recombination velocity (S2) track the density of extended defects near the epilayer/substrate interface. These findings establish deep-UV TRPL as a practical and nondestructive method for evaluating 4H–SiC epitaxial layer quality, providing insight into recombination mechanisms that influence power device performance and reliability.