Effect of Gate Voltage Stress on InGaAs MOSFET with HfO₂ or Al₂O₃ Dielectric

InGaAs nMOSFETs with Al₂O₃ and HfO₂ as dielectric are analyzed. The devices with Al ₂O₃ show a slightly better subthreshold slope. Both high-κ's have an equal transconductance frequency dispersion (g_m-f). A reduction of g_m-f is reached by scaling the HfO₂ thickness. Positive gate stress leads to an increase in threshold voltage and subthreshold slope for all oxides. DC-g_max degradation is related purely to creation or activation of additional border traps during stress. The RF-g_max is not degraded. Similar time constants hint to a relation between the (semi-)stable degradation of DC-g_max and the threshold voltage increase. For the samples with HfO₂, the effects of gate-stress induced additional border traps can only be detected at low frequencies. The created or activated defects are most likely located deep in the oxide. For Al₂O₃, the effect of additional border traps is also measurable at higher frequencies. The defects are created both closer to the Al₂O₃/InGaAs interface and deeper in the oxide.