Passivation of electrically active defects in Ge-Rich SiGe-on-insulator by Al₂O₃ deposition and subsequent post-deposition annealing

Al₂O₃ deposition and subsequent post-deposition annealing (Al₂O₃-PDA) is proposed as an effective method to passivate electrically active defects in Ge-rich SiGe-on-insulator (SGOI) substrates, which were fabricated using Ge condensation. We found that Al ₂O₃-PDA could not only suppress the surface reaction during Al-PDA, but could also reduce the defect-induced hole concentration in Ge-rich SGOI, which was in the range of 10¹⁶-10¹⁸ cm ^-3 before Al₂O₃-PDA, by approximately one order of magnitude. Al₂O₃-PDA greatly improves the electrical characteristics of a back-gate metal-oxide-semiconductor field-effect transistor fabricated on Ge-rich SGOI.