We describe the electrical properties of atomic layer deposited TiO 2/Al 2O 3 bilayer gate oxides which simultaneously achieve high gate capacitance density and low gate leakage current density. Crystallization of the initially amorphous TiO 2 film contributes to a significant accumulation capacitance increase (∼33) observed after a forming gas anneal at 400°C. The bilayer dielectrics reduce gate leakage current density by approximately one order of magnitude at flatband compared to Al 2O 3 single layer of comparable capacitance equivalent thickness. The conduction band offset of TiO 2 relative to InGaAs is 0.6 eV, contributing to the ability of the stacked dielectric to suppress gate leakage conduction.
|Journal||Applied Physics Letters|
|State||Published - 5 Dec 2011|