Deep level transient spectroscopy was applied to study silicon epitaxial layers of varying thickness grown on silicon‐on‐insulator substrates formed by oxygen implantation. For 3‐μm‐thick layers no traps were detected. For 1.0‐, 2.0‐, and 2.5‐μm‐thick layers electron traps were found with levels 0.34, 0.32, and 0.37 eV below the conduction‐band edge, and corresponding capture cross sections of ∼2.0×10−7, 6.0×10−18, and 5.0×10−7 cm2. These levels were found to be uniformly distributed across the wafer. It was also observed that the trap concentration is a decreasing function of epilayer thickness.