Suyeong Jang, UT-Austin

"Design of BaSnO3/Al2O3 quantum well"

Abstract: Quantum wells are heterostructure that are thin enough to confine particles. They are made up of a larger bandgap "barrier" material sandwiching the smaller bandgap "well" material. Quantum well has been used as lasers, photodetectors, modulators, and switches. We propose a quantum well with huge conduction band offset of 3.5eV consisting of Al₂O₃ as a "barrier" material and BaSnO₃(BSO) as a "well" material. Most commonly used quantum well has been InGaAs/GaAs quantum well, however, their small conduction band offset (much less than 1eV) limits their quantum confinement and only allows for intersubband transition at a mid or far infrared range. Our quantum well allows various intersubband transition from visible light to infrared range. BaSnO₃ has very high mobility(150cm^₂ (Vs)^-1 for La doped BSO thin film on PrScO₃ substrate) and a wide bandgap(~3.1eV) which makes it a great candidate for the transparent conductive films material which has applications such as electrodes for optical devices, interconnections of flat panel display, solar cells and light emitting diodes. Using hybrid MBE, we grow Al₂ O₃/BaSnO₃ quantum well and use Reflection-energy electron diffraction(RHEED) and X-ray photoelectron spectroscopy(XPS) to confirm the film quality and composition. We simulate the possible Energy levels and the wavefunction using Poisson Schrodinger Solver. We grow quantum well with 3 different BSO thickness(6, 11, and 16u.c.) to observe the blue shift of the absorption edge of the heterostructure using the ellipsometry measurement.