Abstract

Recent experiments have demonstrated the advantages of interferometric detection of charge carriers in semiconductors over standard pump-probe absorption techniques.¹-² Specific applications have included, for example, the noninvasive backside optical probing of current and voltage waveforms in an integrated circuit with spatial node resolution and temporal resolution limited by laser pulse duration. We present, in this paper, results of the application of pulsed CO₂ laser interferometry to the detection of two-photon absorption (TPA) generated carriers in intrinsic InSb. A sensitivity to carrier concentration changes that is approximately two orders of magnitude greater than that afforded by sensitive pump-probe transmission measurements is demonstrated.

© 1994 Optical Society of America