Experimental and modeling on atomic layer deposition Al2O3/n-InAs metal-oxide-semiconductor capacitors with various surface treatments

Ex-situ sulfide and HCl wet chemical treatments in conjunction with in-situ trimethyl aluminum (TMA) pretreatment were performed before the deposition of Al2O3 on n-InAs surfaces. X-ray photoelectron spectroscopy analyses show a significant reduction of InAs native oxides after different treatments. Capacitance-voltage (C-V) characterization of Al2O3/n-InAs structures shows that the frequency dispersion in accumulation regime is small (<0.75% per decade) and does not seem to be affected significantly by the different surface treatments, whereas the latter improves depletion and inversion behaviors of the nMOS capacitors. The interface trap density profiles extracted from simulation show mainly donor-like interface states inside the InAs bandgap and in the lower part of the conduction band. The donor-like traps inside the InAs bandgap and in the lower part of the conduction band were significantly reduced by using wet chemical plus TMA treatments, in agreement with C-V characteristics.