Electrical and chemical characteristics of Al2O3/InP metal-oxide-semiconductor capacitors

The interface trap density (Dit) and bonding at the Al2O3/InP interface was investigated using capacitance-voltage (C-V) measurements and X-ray photoelectron spectroscopy (XPS). The Dit extracted using C-V measurements show a peak near midgap and a tail, which extends into the InP conduction band. After post high-k deposition annealing, only midgap Dit increases while minimal change in conduction band Dit is observed. The magnitude of extracted Dit is higher for the Al2O3/InP interface compared to the HfO2/InP interface. XPS analysis shows that the native oxides at the Al2O3/InP interface are more phosphorous rich than for HfO2/InP interface.