Materials Science in Semiconductor Processing vol:9 issue:04/05/07 pages:721-726
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/f(gamma) type, with gamma > 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 alpha = 6.5 x 10(7) cm(-1) for the Ge/HfO2 system, the extracted volume and surface trap densities are in the range of 1 x 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/HfO2/ TiN-TaN MOSFETs. (C) 2006 Elsevier Ltd. All rights reserved.