Near infrared to visible intersubband transitions in all-oxide quantum wells using BaSnO₃

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Quantum wells (QWs) are made up of a larger bandgap “barrier” material sandwiching the smaller bandgap “well” material. Recently, quantum well structures using metal oxides such as SrTiO₃ (STO)/LaAlO₃ have been reported. They boast a rather large conduction band offset of ~2.3eV but suffer from large effective mass of STO (used as their “well” material). On the other hand, BaSnO₃ has a small effective mass of m* [subscript BSO] = 0.2m [subscript e] that allows for larger spacing of the QW energy levels. BaSnO₃ also, has very high mobility (150cm²(Vs)⁻¹) and a wide bandgap (~3.1eV) making it a great candidate in applications calling for transparent conductive films. We will discuss MBE-grown Al₂O₃/BaSnO₃ quantum wells demonstrating a high level of confinement. We have grown different thickness of our BSO layer and performed many characterizations on our quantum well such as XRD, XRR, RHEED, XPS, and ellipsometry measurement. The quantum wells in this thesis can allow intersubband transitions from visible to infrared range enabling many applications.



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