In situ metal-organic chemical vapor deposition atomic-layer deposition of aluminum oxide on GaAs using trimethyaluminum and isopropanol precursors

In situ atomic-layer deposition (ALD) of ${\mathrm{Al}}_2{\mathrm{O}}_3$ on $p\text{-}\mathrm{Ga}\mathrm{As}$ in metal-organic chemical vapor deposition system is demonstrated in this article. Isopropanol was chosen as the oxygen source for ${\mathrm{Al}}_2{\mathrm{O}}_3$ ALD, instead of common ${\mathrm{H}}_2\mathrm{O}$ . The ALD mechanism is discussed and it is proposed that water does not form in the process. The saturation growth rate of ${\mathrm{Al}}_2{\mathrm{O}}_3$ is about $0.8\mathrm{\AA }∕\text{cycle}$ . X-ray photoetectron spectroscopy depth profiles were performed and no arsenic oxide is observed at the interface. The capacitance-voltage measurements show a small accumulation capacitance dispersion and voltage shift in the depletion region. The interfacial defect density near the midgap of the GaAs bandgap has been determined with the conductance-frequency method. The interfacial defect density is determined as $2.5\times {10}^{11}{\mathrm{eV}}^{-1}{\mathrm{cm}}^{-2}$ at the midgap of the GaAs.