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 Al2O3 on p-GaAs in metal-organic chemical vapor deposition system is demonstrated in this article. Isopropanol was chosen as the oxygen source for Al2O3 ALD, instead of common H2O. The ALD mechanism is discussed and it is proposed that water does not form in the process. The saturation growth rate of Al2O3 is about 0.8Å∕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 2.5×1011eV−1cm−2 at the midgap of the GaAs.