Very Low Leakage Current of High Band-Gap Al2O3 Stacked on TiO2/InP Metal–Oxide–Semiconductor Capacitor with Sulfur and Hydrogen Treatments

Abstract

High dielectric TiO2 film on InP treated by (NH4)2S shows improved electrical characteristics due to the removal of native oxides. Post-metallization annealing (PMA) can provide hydrogen ions, which effectively passivate defects in TiO2/InP film and interface, further improve electrical characteristics but still with high thermionic emission leakage due to low band-gap TiO2. For high band-gap Al2O3 stacked on PMA-TiO2/S–InP MOS structure with equivalent oxide thickness of 1.8 nm, the leakage current densities can be decreased as low as 1.5×10-8 and 2.2×10-7 A/cm2 at ±2 V, and the interface state density is 3.1×1011 cm-2 eV-1.