Influence of the Ge concentration in the virtual substrate on the low frequency noise in strained-Si surface n-channel metal-oxide-semiconductor field-effect transistors

Abstract

We report on low frequency noise and field-effect mobility in strained-Si surface n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) grown on relaxed virtual substrates with a Ge concentration varying between 0% and 30%. An increased Ge concentration results in higher intrinsic field-effect mobility, increasing from 380cm2V−1s−1 for the unstrained channel to 865cm2V−1s−1 for the strained-Si MOSFET on 30% relaxed SiGe virtual substrate. However, the higher mobility is traded off for increased substrate leakage currents and increased 1∕f (flicker) noise. It is suggested that flicker noise is due to traps in the oxide layer. The density of traps increases from 2×1017eV−1cm−3 for 0% Ge to 2.3×1018eV−1cm−3 for the 30% Ge virtual substrate.