Low-frequency noise (LFN) characteristics under OFF-state stress (OSS), which degrade device performance, were investigated in n-channel MOSFETs. The power spectral density (PSD) was analyzed by investigating the LFN and the border traps located in the gate oxide were extracted along a depth direction perpendicular to the silicon (Si) channel surface. The holes generated by band-to-band tunneling (BTBT) in the overlap region between a drain and a gate were found to be more detrimental to device performance than channel hot-carriers created by impact ionization.