Improved electrical properties of Ge metal-oxide-semiconductor capacitors with high- k HfO 2 gate dielectric by using La 2 O 3 interlayer sputtered with/without N 2 ambient

Abstract

The electrical properties of n-Ge metal-oxide-semiconductor (MOS) capacitors with HfO 2 /LaON or HfO 2 / La 2 O 3 stacked gate dielectric (LaON or La 2 O 3 as interlayer) are investigated. It is found that better electrical performances, including lower interface-state density, smaller gate leakage current, smaller capacitance equivalent thickness, larger k value, and negligible C-V frequency dispersion, can be achieved for the MOS device with LaON interlayer. The involved mechanism lies in that the LaON interlayer can effectively block the interdiffusions of Ge, O, and Hf, thus suppressing the growth of unstable GeO x interlayer and improving the dielectric/Ge interface quality. © 2010 American Institute of Physics.