Optical Dielectric Function Modeling and Electronic Band Lineup Estimation of Amorphous High-k LaGdO3Films

Optical constants of pulsed laser ablated amorphous high-k LaGdO 3 (a-LGO) thin films on quartz (0001) substrates were measured and analyzed. Refractive index ( n ∼ 2.05–2.29) and extinction coefficient ( k ∼ 0.004–0.017) were parameterized by analysis of the UV/Visible transmission spectra employing a Cauchy-Urbach dispersion model in the 300–750 nm spectral window and confirmed the applicability of this model in this wavelength region. The composition and chemistry of these dielectric films were studied by utilizing ATR-FTIR spectroscopy. The deduced pinning factor ( S ), 0.5 suggests that LGO/Si is an interacting interface. The parameter S was applied in the Cowley-Sze relation to estimate the interface trap density ( D it ) to be 1.08 × 10 13 states cm −2 eV −1 . As grown LGO/p-Si heterojunction showed a downward Fermi-level (FL) pinning of 0.39 ± 0.02 eV. A complete Type I straddled band lineup of this gate dielectric/semiconductor heterostructure was determined by applying the charge neutrality level (CNL) model. The CNL of LGO was deduced to be 2.11 ± 0.05 eV above valence band maximum.