Defectiveness control of epitaxial 4H-SiC by thermal annealing at low temperature and high pressure O2

Interface and bulk defects are detrimental for the performance of 4H-Silicon Carbide (4H-SiC) electronic devices and thermal annealing is an essential procedure for the defects’ passivation and material optimization. In this study, we explore the impact on defectiveness of high-pressure (800 PSI ≈ 55 bar) thermal annealing in oxygen and helium atmospheres at 400 °C on 4H-SiC by examining exciton lifetimes. Three wafer types, representing different stages of device processing, were analyzed: (A) a bare epitaxial layer, (B) an oxide-coated sample, and (C) a sample that underwent post-oxide deposition annealing in nitric oxide (NO). Photoluminescence decay measurements after O₂ annealing show an increased exciton lifetime for the oxide-covered sample, a significant reduction for the bare epitaxial layer and no effects for NO post-deposition annealed sample. Comparisons with helium-annealed samples highlight the influence of oxygen in low-temperature annealing of SiC, presenting \:O₂ -based processing as a promising starting point for developing alternative post-deposition annealing methods.