3 research outputs found
Atomic Layer Deposition of Al<sub>2</sub>O<sub>3</sub> onto Sn-Doped In<sub>2</sub>O<sub>3</sub>: Absence of Self-Limited Adsorption during Initial Growth by Oxygen Diffusion from the Substrate and Band Offset Modification by Fermi Level Pinning in Al<sub>2</sub>O<sub>3</sub>
The growth of Al<sub>2</sub>O<sub>3</sub> onto Sn-doped
In<sub>2</sub>O<sub>3</sub> (ITO) by atomic layer deposition (ALD)
was studied in situ using X-ray photoelectron spectroscopy. Significant
diffusion of oxygen from the substrate destroys the self-terminated
monolayer adsorption of the metal precursor and results in a nominal
initial growth per cycle of >1 nm. The observed mechanism precludes
the preparation of monolayer thick Al<sub>2</sub>O<sub>3</sub> films
on ITO substrates by ALD. The energy band alignment at the ITO/Al<sub>2</sub>O<sub>3</sub> interface is significantly different from that
obtained when magnetron sputtering is used for the deposition of Al<sub>2</sub>O<sub>3</sub> onto ITO [Gassenbauer et al., <i>Phys.
Chem. Chem. Phys.</i> <b>2009</b>, <i>11</i>,
3049]. The difference is attributed to a pinning of the Fermi level
in the ALD-Al<sub>2</sub>O<sub>3</sub> layer close to midgap, which
is attributed to the incorporation of hydrogen in the film during
growth