Bias temperature instability (BTI) is one of the critical device degradation mechanisms in poly-Si/SiON and metal gate/high-k complementary metal-oxide-semiconductor (CMOS) technologies. Using the pre- and post-BTI flicker noise measurements, we investigated the bulk trap density, N-t, in both of these technologies. The low-frequency noise spectra were predominantly of 1/f(gamma) type with gamma < 1 for NMOS and similar to 1 for PMOS. For SiON based technologies, the lower V-TH degradation due to PBTI was noticed while considerable VTH degradation was observed for NBTI in both SiON and MGHK technologies. Both MGHK and SiON pFETs show a clear increase in the effective volume trap density, N-t, after NBTI. The increase in N-t in MGHK n-MOSFETs during PBTI is markedly higher than that in MGHK p-MOSFETs during NBTI. (C) 2017 Elsevier Ltd. All rights reserved.