(Invited) Border-Trap Characterization for Ge Gate Stacks with Thin GeO_X layer Using Deep-Level Transient Spectroscopy

The deep-level transient spectroscopy (DLTS) measurements for the SiO₂/GeO₂/Ge gate stacks represent the different pulse height dependences of the border trap (BT) signals for p- and n-MOSCAPs. We propose the tunneling models to/from BT in GeO₂ to explain the difference. Based on this model, the BTs in Al₂O₃/GeO_x/p-Ge gate stacks were characterized using DLTS. Through evaluating the gate stacks with different GeO_x thickness, the respective BTs in Al₂O₃, Al₂O₃/GeO_x interface region, and GeO_x were detected. The density of BT (N_bt) in Al₂O₃ (6~9 × 10¹⁷ cm^-3) is lower than those in GeO_x (~2 × 10¹⁸ cm^-3), and the highest N_bt (~1 × 10¹⁹ cm^-3) was found in Al₂O₃/GeO_x interface region. Ge p-MOSFETs with Al₂O₃/GeO_x/p-Ge gate stacks were fabricated and analyzed. We confirmed that the ITs and the BTs near to valence band edge of Ge affect the effective mobility of Ge p-MOSFETs in high field region.