This paper reports on the results of an investigation into the nature of photoluminescence upconversion at $\mathrm{GaAs}/\mathrm{InGa}{\mathrm{P}}_2$ interfaces. Using a dual-beam excitation experiment, we demonstrate that the upconversion in our sample proceeds via a sequential two-photon optical absorption mechanism. Measurements of photoluminescence and upconversion photoluminescence revealed evidence of the spatial localization of carriers in the $\mathrm{InGa}{\mathrm{P}}_2$ material, arising from partial ordering of the $\mathrm{InGa}{\mathrm{P}}_2$. We also observed the excitation of a two-dimensional electron gas at the $\mathrm{GaAs}/\mathrm{InGa}{\mathrm{P}}_2$ heterojunction that manifests as a high-energy shoulder in the GaAs photoluminescence spectrum. Furthermore, the results of upconversion photoluminescence excitation spectroscopy demonstrate that the photon energy onset of upconversion luminescence coincides with the energy of the two-dimensional electron gas at the $\mathrm{GaAs}/\mathrm{InGa}{\mathrm{P}}_2$ interface, suggesting that charge accumulation at the interface can play a crucial role in the upconversion process.

• Received 29 February 2016
• Revised 14 April 2016

DOI:https://doi.org/10.1103/PhysRevB.93.235303

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Published by the American Physical Society