Interference Effects in Electromodulation Spectroscopy Applied to GaAs-Based Structures: A Comparison of Photoreflectance and Contactless Electroreflectance
Journal Article - Open Access
Stanford University Stanford United States
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In this letter, we show that the oscillation features OFs usually observed in photoreflectance PR spectra of GaAs-based structures grown on the n-type GaAs substrate below the GaAs fundamental gap could be eliminated completely by applying the contactless electroreflectance CER instead of PR. This finding confirms that the origin of OFs is the modulation of the refractive index in the sample due to the generation of additional carriers by the modulated pump beam. In the case of CER spectroscopy, any additional carriers are not generated during the modulation hence CER spectra are free of OFs. This advantage of CER spectroscopy is very important in investigations of all structures for which OFs are present in PR spectra. In order to illustrate this advantage of CER spectroscopy we show PR and CER spectra measured first for the GaAs epilayer and next for more complicated step like GaInNAsSbGaNAsGaAs quantum well structures.
- Atomic and Molecular Physics and Spectroscopy