Improvement of Carrier Lifetimes in Highly Al-Doped p-Type 4H-SiC Epitaxial Layers by Hydrogen Passivation

Abstract

Carrier lifetimes in a highly Al-doped p-type epilayer (NA = 1×1018 cm-3) are investigated by differential microwave photoconductance decay (µ-PCD) measurements. A carrier lifetime of 310 ns in the as-grown p-type epilayer decreases to 90 ns by thermal treatment in Ar, O2, or N2 atmospheres (>700 °C), and recovers to 300 ns by H2 annealing (>750 °C). Hydrogen is detected at a concentration of (2–3)×1015 cm-3 in the H2-annealed epilayer. These results suggest that a lifetime killer exists in the p-type epilayer, limiting the carrier lifetime to 90 ns and is passivated by hydrogen annealing, resulting in the improved carrier lifetime of 300 ns.