Low-Frequency Noise Characterization of GeOx Passivated Germanium MOSFETs

The gate-stack quality of planar MOSFETs fabricated in Ge-on-Si substrates and passivated by a GeO
_x
interfacial layer is evaluated by low-frequency noise analysis. It is shown that for both n- and p-channel transistors predominantly 1/
$f^{\gamma }$
noise (
$\gamma \sim 1$
) has been observed, which originates from number and correlated mobility fluctuations. The oxide trap density and mobility scattering coefficient derived from the input-referred voltage noise power spectral density are demonstrated to be significantly higher for nMOSFETs than for pMOSFETs with the same gate-stack, which explains the low electron mobility.