Passivation of Ge(100)/GeO2/high-kappa gate stacks using thermal oxide treatments

The physical and electrical properties of Ge/GeO2/high-kappa gate stacks, where the GeO2 interlayer is thermally grown in molecular oxygen, are investigated. The high-kappa layer (ZrO2, HfO2, or Al2O3) is deposited in situ on the GeO2 interlayer by atomic layer deposition. Detailed analysis of the capacitance-voltage and conductance-frequency characteristics of these devices provides evidence for the efficient passivation of the Ge (100) surface by its thermal oxide layer. A larger flatband voltage hysteresis is observed in HfO2-based gate stacks, as compared to Al2O3 gate stacks, which is possibly related to the more pronounced intermixing observed between the HfO2 and GeO2. (c) 2007 The Electrochemical Society.