Abstract by Karen Membreno
Chemistry and Biochemistry
Al Oxidation as Function of Ultrathin MgF2 Coatings
Aluminum (Al) is an inexpensive metal and has the widest bandgap of all metals and functions as the best reflector. NASA uses Al reflectors in the Hubble space telescope, but Al oxidizes rapidly which makes full reflection impossible. Magnesium Fluoride (MgF2) is used to prevent this oxidation. As such, we measured Al oxidation rate as a function of MgF2 thickness for creation of thin film protection layers. We deposited different MgF2 thicknesses (measured by quartz crystal monitoring (QCM)) onto freshly deposited Al in a Denton evaporator to minimize Al oxidation. Next we measured the Al oxidation rate as a function of MgF2 thickness using spectroscopic ellipsometry (SE). Because of correlation between the MgF2 and Al2O3 layers when using SE, X-ray photoelectron spectroscopy (XPS) was used to verify MgF2 thickness. With these measurements, we made a graphical model by plotting the rate of aluminum oxidation as a function of MgF2 film thicknesses. This graphical model allows us to predict the oxidation rates as functions of our MgF2 coatings.