Lanthanum germanate as dielectric for scaled Germanium metal-oxide-semiconductor devices

Abstract

We report a study of La2O3 with lanthanum germanate (LGO) as interfacial layer, or LGO alone as a gate dielectric candidate for scaled germanium metal-oxide-semiconductor devices. Capacitance-voltage (C-V) analysis of as-deposited samples of various oxide thicknesses show a La2O3 with k value of ∼24-27 with an interfacial LGO with k value of ∼12. Upon O2 annealing, the oxides fully transform into LGO without an interfacial layer. The paper also discusses flatband voltage (Vfb) shifts with oxide thickness, from which positive fixed charges in La2O3 can be deduced. It is also shown that these charges are strongly reduced upon the O2 anneal and LGO formation. © 2009 Elsevier B.V. All rights reserved.