Optical Detection of Parasitic Channels of Vertically Stacked Ge0.98Si0.02 nGAAFETs

The distinct photoresponse of the floating channels and the parasitic channels can be a signature to check the existence of the parasitic channel. The photoresponse of the sole parasitic channel mainly shows the photocurrent (
${I}_{\text {ph}}$
), while the photoresponse of the sole floating channels without parasitic channel shows the negative threshold voltage shift (
$\Delta {V}_{\text {T}}$
) for nFET. The device with both the floating channels and the parasitic channel shows both photocurrent and negative threshold voltage shift under exposure.