Atomic Layer Deposition and in Situ Characterization of Ultraclean Lithium Oxide and Lithium Hydroxide

We demonstrate the ultraclean atomic layer deposition (ALD) of Li 2 O and LiOH using lithium tert -butoxide (LiO t Bu) precursor with H 2 O and plasma O 2 as oxidants, along with conversion of Li 2 O and LiOH products to Li 2 CO 3 upon CO 2 dosing. Using LiO t Bu and H 2 O results in LiOH below 240 °C and Li 2 O above 240 °C for otherwise identical process parameters. Substituting plasma O 2 as the oxidation precursor results in a combination of Li 2 CO 3 and Li 2 O products, indicating modification of the ALD reaction preventing volatilization of the C from the Li precursor. The chemistry of the films is definitively characterized for the first time with XPS utilizing an all-UHV transfer procedure from the ALD reactor. We use in situ UHV gas dosing to investigate the reaction mechanisms of ALD Li 2 O and LiOH with H 2 O and CO 2 to simulate reactions upon air exposure. Lastly, we employ in situ spectroscopic ellipsometry to determine the reaction kinetics of thermal LiOH decomposition, and we report an activation energy of 112.7 ± 0.6 kJ/mol.