SiGe-on-insulator (SGOI) substrates with different Ge fraction (Ge%) were fabricated using Ge condensation technique. High acceptor concentration (N A) in SGOI layer and interface-trap density (D it) at SGOI/buried oxide (BOX) interface were found by using back-gate metal-oxide-semiconductor field-effect transistor method. For the reduction of high N A and D it , Al deposition and the subsequent post-deposition annealing (Al-PDA) was carried out. As a comparison, a forming gas annealing (FGA) was also performed in H 2 ambient. It was found that both Al-PDA and FGA effectively reduced N A and D it for low-Ge% SGOI. However, with an increase in Ge%, FGA became less effective while Al-PDA was very effective for the reduction of N A and D it .

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 Al2O3-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.

a b s t r a c tA method of Al 2 O 3 deposition and subsequent post-deposition annealing (Al 2 O 3 -PDA) was proposed to passivate electrically active defects in Ge-rich SiGe-on-insulator (SGOI) substrates, which were fabricated using Ge condensation by dry oxidation. The effect of Al 2 O 3 -PDA on defect passivation was clarified by surface analysis and electrical evaluation. It was found that Al 2 O 3 -PDA could not only suppress the surface reaction during Al-PDA in our previous work [Yang H, Wang D, Nakashima H, Hirayama K, Kojima S, Ikeura S. Defect control by Al-deposition and the subsequent post-annealing for SiGe-on-insulator substrates with different Ge fractions. Thin Solid Films 2010; 518: 2342-5.], but could also effectively passivate p-type defects generated during Ge condensation. The concentration in the range of 10 16 -10 18 cm À3 for defect-induced acceptors and holes in Ge-rich SGOI drastically decreased after Al 2 O 3 -PDA. As a result of defect passivation, the electrical characteristics of both back-gate p-channel and nchannel metal-oxide-semiconductor field-effect transistors fabricated on Ge-rich SGOI were greatly improved after Al 2 O 3 -PDA.

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. We found that Al2O3-PDA could not only suppress the surface reaction during Al-PDA, but could also effectively reduce the defect-induced acceptor and hole concentration in Ge-rich SGOI. Al2O3-PDA greatly improves the electrical characteristics of a back-gate metal-oxide-semiconductor field-effect transistor fabricated on Ge-rich SGOI.