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Effects of a cap layer on built-in electric fields of AlxGa1-xN/GaN heterostructures non-destructively probed by Franz-Keldysh oscillations

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Abstract.

We have investigated electric field strengths in the AlxGa1-xN layer, FAlGaN's, of AlxGa1-xN/GaN heterostructures with and without a GaN cap layer using photoreflectance (PR) spectroscopy. Franz-Keldysh oscillations (FKOs) from the AlxGa1-xN layer are clearly observed in the PR spectra. It is found from analysis of the FKOs that stacking of the cap layer causes a remarkable enhancement of FAlGaN. This fact demonstrates that the FKO profile is a non-destructive probe for a change of built-in electric field strength induced by a cap layer. Numerical calculations of FAlGaN based on a Schrödinger-Poisson equation clarify that the magnitude of the enhancement of FAlGaN is dominated by the cap-layer thickness.

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Takeuchi, H., Yamamoto, Y., Kamo, Y. et al. Effects of a cap layer on built-in electric fields of AlxGa1-xN/GaN heterostructures non-destructively probed by Franz-Keldysh oscillations. Eur. Phys. J. B 52, 311–314 (2006). https://doi.org/10.1140/epjb/e2006-00302-y

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