The Effect of NH3 on the interface of HfO2 and Al2O3 films on GaAs (100) surfaces

In this letter, we investigate the effects of heat treatment under NH3 ambient on the Ga-O at the interface between GaAs and high-k dielectric materials deposited by atomic layer deposition (ALD). Compared with the heat treatment results under N-2 ambient, the monochromatic x-ray photoelectron spectroscopy (XPS) analysis reveal that the formation of Ga-O is greatly suppressed when under NH3 ambient, both at 500 degrees C and 700 degrees C, for HfO2. However, similar experiments for Al2O3 deposited by atomic layer deposition (ALD) show that the effect of NH3 heat treatment is minimal. We examine the different reaction mechanisms of the nitridation processes for the two different high-k dielectric materials on GaAs. Also, the capacitance-voltage (C-V) properties of metal-insulator-semiconductor capacitors (MISCAP) with Pt electrodes are experimentally examined for various annealing temperatures and ambient conditions.