A new offset technique for suppression of spurious signals in photoreflectance spectra

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