Improved interfacial state density in Al2O3/GaAs interfaces using metal-organic chemical vapor deposition

In situ deposition of Al2O3 on GaAs was performed by chemical-vapor-deposition (CVD) with trimethyaluminum and isopropanol as precursors. A gallium-rich region in the Al2O3 thin film above the interface was spontaneously formed via the in situ CVD process. Ga-enrichment of the interface was observed using secondary ion mass spectrometry (SIMS) depth profile measurement. X-ray photoelectron spectroscopy (XPS) results show that the gallium-rich region consists of Al2O3 and Ga2O3, but no As2O3 was observed. The Ga2O3-Al2O3 layer above the oxide/GaAs interface reduces the frequency dispersion as measured with capacitance-voltage (C-V) characteristics and lowers the interfacial state density as compared to atomic-layer-deposition *(ALD) deposited films which do not display this gallium enrichment above the interface. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3428790]