Relationship between interface state generation and substrate hole current in InGaAs metal-oxide-semiconductor (MOS) interfaces

Abstract

The relationship between substrate hole currents and interface state generation in Al2O3/InGaAs n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) is experimentally studied for the MOSFETs with three different Al2O3 thicknesses of 3.2, 5.2, and 8.2 nm. The constant positive gate bias stress is applied. Then, the substrate hole current, monitored in the carrier separation setup, is clearly observed for the InGaAs n-channel MOSFETs. It is found that the density of the generated interface states (ΔDit) is uniquely represented as a function of the total hole fluence (Nhole), given by integrating the substrate hole current over time, not the total electron fluence. This experimental result strongly supports that interface state generation is triggered by holes induced by electrical stress, regardless of the thickness of Al2O3. It is also found that ΔDit in 3.2- and 5.2-nm-thick Al2O3 MOSFETs, expressed by the universal single line against Nhole, is lower than that in 8.2-nm-thick Al2O3 MOSFETs, which can be explained by the difference of the origin of the hole generation in the Al2O3/InGaAs metal-oxide-semiconductor interface. Judging from the similarity of these features with ΔDit in SiO2/Si n-MOSFETs reported previously, the Al2O3/InGaAs interfaces have the same physical origin of interface state generation as SiO2/Si interfaces.