Comparison of the interfacial and electrical properties of HfAlO films on Ge with S and GeO2 passivation

We report the characteristics of HfAlO films deposited on S- and GeO2-passivated Ge substrates at 150 °C by atomic layer deposition technique using Hf(NO3)4 and Al(CH3)3 as the precursors. The x-ray photoelectron spectroscopic analyses reveal that GeO2 passivation is more effective to suppress GeOx formation than S passivation. It is demonstrated that the capacitors with GeO2 passivation exhibit better electrical properties with less hysteresis, improved interface quality, and reduced leakage current. These results indicate that using GeO2 as an interfacial layer may be a promising approach for the realization of high quality Ge-based transistor devices.