Ge N-Channel MOSFETs with ZrO2 Dielectric Achieving Improved Mobility

Abstract

High-mobility Ge nMOSFETs with ZrO2 gate dielectric are demonstrated and compared against transistors with different interfacial properties of ozone (O3) treatment, O3 post-treatment and without O3 treatment. It is found that with O3 treatment, the Ge nMOSFETs with ZrO2 dielectric having a EOT of 0.83 nm obtain a peak effective electron mobility (μeff) of 682 cm2/Vs, which is higher than that of the Si universal mobility at the medium inversion charge density (Qinv). On the other hand, the O3 post-treatment with Al2O3 interfacial layer can provide dramatically enhanced-μeff, achieving about 50% μeff improvement as compared to the Si universal mobility at medium Qinv of 5 × 1012 cm−2. These results indicate the potential utilization of ZrO2 dielectric in high-performance Ge nMOSFETs.