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Low-frequency noise characteristics are reported for TaSiN-gated n-channel MOSFETs with atomic-layer deposited HfO2 on thermal SiO2 with stress-relieved preoxide (SRPO) pretreatment. For comparison, control devices were also included with chemical SiO2 resulting from standard Radio Corporation of America clean process. The normalized noise spectral density values for these devices are found to be lower when compared to reference poly Si gate stack with similar HfO2 dielectric. Consequently, a lower oxide trap density of ∼4×1017 cm-3eV-1 is extracted compared to over 3×1018 cm-3eV-1 values reported for poly Si devices indicating an improvement in the high-κ and interfacial layer quality. In fact, this represents the lowest trap density values reported to date on HfO2 MOSFETs. The peak electron mobility measured on the SRPO devices is over 330 cm2/V·s, much higher than those for equivalent poly Si or metal gate stacks. In addition, the devices with SRPO SiO2 are found to exhibit at least ∼10% higher effective mobility than RCA devices, notwithstanding the differences in the high-κ and interfacial layer thicknesses. The lower Coulomb scattering coefficient obtained from the noise data for the SRPO devices imply that channel carriers are better screened due to the presence of SRPO SiO2, which, in part, contributes to the mobility improvement.