Optical constants of germanium and thermally grown germanium dioxide from 0.5 to 6.6eV via a multisample ellipsometry investigation

Abstract

Thermal GeO2 oxides up to 136 nm thickness were produced by annealing Ge wafers in pure oxygen at 550 °C and 270 kPa pressure for up to 10 h. The oxidation kinetics followed the Deal–Grove law. Using multisample spectroscopic ellipsometry for a series of five thermal oxides with different thicknesses, the complex dielectric functions of Ge and GeO2 were determined from 0.5 to 6.6 eV, for thin-film metrology applications in Ge-based microelectronics and photonics. The dispersion of the GeO2 layer was modeled with a simple Tauc-Lorentz oscillator model, but a more complicated dispersion with eight parametric oscillators was required for Ge. A reasonable fit to the ellipsometric angles could be obtained by assuming that all thermal oxides can be described by the same dielectric function, regardless of thickness, but a slight improvement was achieved by allowing for a lower density oxide near the surface of the thickest films. The authors compare their results with literature data for Ge and bulk and thin-film GeO2.

Effects of Temperature on the Morphology and Optical Properties of Spark Discharge Germanium Nanoparticles

“…According to the Mie theory, the extinction cross-section could be presented as a sum of multipole harmonic series [ 32 , 33 ]. Taking into account data presented in the work [ 34 ] on Ge complex refractive index spectrum, we calculated the average extinction cross-section of nanoparticles in correspondence with the obtained distribution. For the particles with an amorphous matrix we take into consideration the presence of an amorphous shell with a refractive index of 1.7 for GeO 2 .…”

Numerical investigations of the impact of buffer germanium composition and low cost fabrication of Cu2O on AZO/ZnGeO/Cu2O solar cell performances

“…From the linear interpolation, the bandgap energy is estimated to be 4.97 eV for the Zn 0.38 Ge 0.62 O compound by taking into account a 5.95 eV bandgap energy for germanium oxide [45] and a 3.37 eV bandgap energy for zinc oxide [24]. In a similar way, the interpolated electron affinity is x ZGO = 3.11 eV using an electron affinity of 2.5 eV for germanium oxide [46] and 4.1 eV for zinc oxide [8].…”

Plasma Cell Sensor Using Photonic Crystal Cavity

“…1 [51]. We select and 2 as dielectric materials because they have high contrast in refractive indices and will make a wide photonic band gap in the selected region (infra-red) with low loss (near to zero Extinction coefficient) in this regions, as will mentioned in the next section [52,53].…”