Atomic layer deposited (ALD) alumina is one of the most widely used amorphous coating materials, as it is a model ALD system with well-understood surface chemistry . ALD alumina was first employed as a high-k dielectric and is present in applications across a range of electronic devices from solar cells to battery electrodes and field-effect transistors. Amorphous alumina (a-Al2O3) is a wide band-gap insulator which enables surface passivation, interface stability, and protects against degradation as a coating material . These properties have increased the capacity retention of Li-ion battery electrodes , enhanced the lifetime of perovskite solar cells , and improved the catalytic capabilities of metalorganic frameworks . Given its clear widespread applications, an atomic level model of a-Al2O3 would be indispensable to the device physics community.