1/f noise performance of MOSFETs with HfO2 and metal gate on Ge-on-insulator substrates

The low frequency (1/f) noise performance of n- and p-MOSFETs with HfO2 and TiN–TaN metal gate on GeOI substrates has been investigated. The LF noise spectra are of the 1/fγ type, with γ>1. The current noise spectral density is typically one decade higher than for silicon counterparts. The behavior of the noise characteristics points to carrier trapping as the prevailing 1/f noise mechanism. Using a tunneling coefficient α=6.5×107 cm−1 for the Ge/HfO2 system, the extracted volume and surface trap densities are in the range of 1×1020/cm3 eV and a few 1012/cm2, respectively. This is of the same order as the interface trap densities, obtained from charge pumping. It is believed that the Ge/interfacial layer (IL) quality could be responsible for the significantly higher trap densities and noise, compared with Si/HfO2/ TiN–TaN MOSFETs.