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5 March 2020 Electronic coupling in ZnO asymmetric quantum wells for intersubband cascade devices
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Proceedings Volume 11281, Oxide-based Materials and Devices XI; 112811S (2020)
Event: SPIE OPTO, 2020, San Francisco, California, United States
Recently Zinc Oxide has received a renewed attention for the realization of intersubband devices such as quantum cascade lasers (QCLs). Indeed this material is predicted to be able to tackle the main limitation of current terahertz (THz) QCLs: the limited operation temperature. We report the observation of electronic coupling within ZnO/(Zn, Mg)O asymmetric quantum wells (QWs), first step towards this goal. Samples were grown by molecular beam epitaxy (MBE) with surfaces down to 0.4 nm. X-ray reflectivity (XRR) was used for thickness measurements checking and for the investigation of the interface quality. Atomic resolution scanning transmission electron microscopy (STEM) images reveals that we are able to grow 2 monolayers (MLs) thin (Zn, Mg)O barriers in a reproducible way while keeping abrupt interfaces. Room temperature (RT) photoluminescence (PL) spectra show that QWs are still coupled when separated by a 1.0 nm thick barrier. On the contrary, a 4.0 nm thick barrier allows no coupling. Doped samples were investigated by absorption experiment. Absorption spectra were successfully fitted by a theoretical model, proving a clear electronic coupling in our heterostructures. This demonstration allows us to seriously envision the realization of ZnO based intersubband devices.
© (2020) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
N. Le Biavan, B. Meng, M. Montes Bajo, J. Tamayo-Arriola, A. Torres-Pardo, D. Lefebvre, M. Hugues, A. Hierro, J. Faist, and J.-M. Chauveau "Electronic coupling in ZnO asymmetric quantum wells for intersubband cascade devices", Proc. SPIE 11281, Oxide-based Materials and Devices XI, 112811S (5 March 2020);

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