In-situ deposited HfO2 and Y2O3 on epi-Si/p-Ge—a comparative study of the interfacial properties and reliability

Abstract

Abstract Single-crystal Si films six-monolayers in thickness were epitaxially grown on Ge(001) surface to minimize the formation of undesirable GeO x with subsequent deposition of HfO2 and Y2O3. The interfacial properties and reliability of the in-situ deposited high-κ oxides on epi-Si/p-Ge(001) were compared. We have achieved interface trap density (D it) values of (1–3) × 1011 eV−1cm−2 in the Y2O3/epi-Si/p-Ge(001), which are two times lower than those of the HfO2/epi-Si/p-Ge(001). The capacitance-equivalent-thicknesses under different annealing conditions were extracted to analyze the interdiffusion in the gate stacks under various thermal treatments. Y2O3/epi-Si/Ge exhibited higher thermal stability than HfO2/epi-Si/Ge. In both high-κ’s gate stacks, the effective charge sheet densities (ΔN eff) are lower than the targeted value of 3 × 1010 cm−2. Compared to the Y2O3 gate stacks, attainment of a high acceleration factor of 11 in the HfO2 gate stacks suggested an improved defect-carrier decoupling in the latter stacks.