1/f Noise and trap density in n-channel strained-Si/SiGe modulation doped field effect transistors (original) (raw)

Noise and trap density in n-channel strained-Si / SiGe modulation doped field effect transistors

2009

The low frequency (1/f) noise characteristics of Schottky-gated strained-Si n-channel modulation doped field effect transistors have been investigated as a function of Ge concentration for different virtual substrates. The gate voltage dependence of the 1/f noise agrees well with the McWhorter carrier number fluctuations model. The trap density (extracted using a Ge dependent potential barrier height and tunnelling constant) is low in devices on thick virtual substrates (Nt = (2–6) 10 cm 3 eV ), and does not degrade with the increase of the Ge concentration from 30% to 40%. This trap density is the same for thin Helax virtual substrates (He ions implanted thin substrate) but increases two orders of magnitude for thin low-temperature grown substrates. 2009 Elsevier Ltd. All rights reserved.

Low-Frequency Noise Characterization of Strained Germanium pMOSFETs

IEEE Transactions on Electron Devices, 2011

Low-frequency noise in strained Ge epitaxial layers, which are grown on a reverse-graded relaxed SiGe buffer layer, has been evaluated for different front-end processing conditions. It has been shown that the 1/f noise in strong inversion is governed by trapping in the gate oxide (number fluctuations) and not affected by the presence of compressive strain in the channel. However, some impact has been found from the type of halo implantation used, whereby the lowest noise spectral density and the highest hole mobility are obtained by replacing the standard As halo by P implantation. At the same time, omitting the junction anneal results in poor device characteristics, which can be understood by considering the presence of a high density of nonannealed implantation damage in the channel and the gate stack near the source and the drain.