1/ f noise performance of MOSFETs with HfO 2 and metal gate on Ge-on-insulator substrates

Abstract

The low frequency (1/ f) noise performance of n- and p-MOSFETs with HfO 2 and TiN–TaN metal gate on GeOI substrates has been investigated. The LF noise spectra are of the 1/ f γ 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=6.5×10 7 cm −1 for the Ge/HfO 2 system, the extracted volume and surface trap densities are in the range of 1×10 20/cm 3 eV and a few 10 12/cm 2 , 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/HfO 2/ TiN–TaN MOSFETs.