Analysis of Oxide Trap Characteristics by Random Telegraph Signals in nMOSFETs With HfO2-Based Gate Dielectrics

Abstract

This letter investigates the oxide trap properties in n-channel metal-oxide-semiconductor field-effect transistors with HfO2 and Hf(1-x)ZrxO(2)/metal gate-stacks by an analysis of random telegraph signals. According to the multiphonon emission theory, the extracted relaxation energies show gate voltage dependence in devices with HfO2-based stacks. This dependence results from the different strengths of vibrations of the nearest neighbor Hf atoms of the oxygen vacancy in the immediate vicinity of the oxide trap. Furthermore, this dependence also induces an abnormal gate voltage dependence in terms of the activation energy required for electron capture. These results are confirmed by comparisons between two HfO2-based devices (HfO2 and Hf(1-x)ZrxO(2)).