Effects of HCl treatment and predeposition vacuum annealing on Al2O3/GaSb/GaAs metal–oxide–semiconductor structures

Abstract

The effects of HCl treatment and predeposition vacuum annealing (VA) on n-type GaSb/GaAs metal–oxide–semiconductor (MOS) structures with the atomic layer deposition (ALD) of Al2O3 dielectrics are studied. We obtained MOS structures with good Fermi level modulation by HCl treatment prior to the deposition of Al2O3. From X-ray photoelectron spectroscopy (XPS) analysis, we found that the Ga2O3 content increases during the Al2O3 deposition, whereas the amounts of Sb components are reduced. The excess growth of Ga2O3 is inhibited by the reductions in the amounts of Sb components by the HCl treatment. Further reductions in the amounts of Sb components are observed following predeposition VA, indicating a lower density of states (Dit). However, the frequency dispersion in the capacitance–voltage (C–V) characteristics increases with predeposition VA at higher temperatures.