Noninvasive sheet charge density probe for integrated silicon devices

Abstract

We report a sensitive new technique for probing dynamic sheet charge density variations in integrated silicon devices. Using a specially designed noninvasive Nomarski phase contrast interferometer a sheet charge density sensitivity of 2.6×108 e/cm2/(Hz)1/2 is extracted from experimental data for 1 mA of detected photocurrent. This charge density sensitivity makes possible μV signal level detection in an active device, and with digital signals the corresponding signal/noise level is sufficiently high that multimegabaud data can be captured in real time.