A NEW OFFSET TECHNIQUE FOR SUPPRESSION OF SPURIOUS SIGNALS IN PHOTOREFLECTANCE SPECTRA

A new technique to suppress the unwanted, spurious signals often encou ntered in photoreflectance spectra from semiconductors and semiconduct or microstructures is described here. This approach utilizes a properl y phase-shifted signal from the reference source that is applied to th e lock-in amplifier's differential input. This paper demonstrates that this new approach is superior to existing methods of background minim ization and is simpler to implement. It is particularly effective when the spurious signal is much larger than the underlying desired trace.