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Spectroscopic ellipsometry characterization of amorphous aluminum nitride and indium nitride thin films

“…The refractive index, n, varies from approximately 2.05-2.35 in the wavelength range 300-1400 nm, with the maximum occurring at about 500 nm. The general behavior of the refractive index of our a-InN films is similar to that of c-InN films [26,27]. The extinction coefficient, κ, varies smoothly from 0.0 to 0.55.…”

Ellipsometric study of a-Be3N2 thin films prepared by radio frequency magnetron sputtering

“…The grain's sizes, shape of the islands and their separations, the substrate, the deposition conditions, and different void fractions [20] significantly alter the effective optical constants. Additionally, the surface conditions and the formation of an oxide layer on the surface of the film could be strongly affecting the ellipsometric measurements [21,22].…”

Optical absorption in amorphous InN thin films

“…The optical constants of the crystalline silicon substrate and silicon dioxide (SiO 2 ) over layer (<2.2 nm) were taken from the literature and were not allowed to vary during the fitting process [13]. Modeling of InN thin films is quite challenging since the optical properties of InN thin films are affected by the amount of disorder in the sample, the deposition rate, impurities, vacuum conditions, lack of a suitable substrate and other factors [14,15]. Surface conditions and the formation of an oxide layer on the surface may also strongly affect the ellipsometric measurements.…”

“…This formulation provides a parameterized model that employs the Lorentz oscillator model along with the Tauc joint density of states for the dielectric response for a collection of single atoms [17]. The model dielectric function, Tauc-Lorentz, employs five fitting parameters [13,14] : the bandgap energy E g , the prefactor A, which includes the optical transition matrix elements, the Lorentz resonant frequency E o , the broadening parameter C and the non-dispersive term e 1 (1). The four fitting parameters, E g , A, E o , and C are in units of energy while e 1 (1) is dimensionless.…”

“…e 1 (1) represents the contribution of the optical transitions at higher energies and appears as an additional fitting parameter [18]. It is usually assumed that e 1 (1) equals unity [14,19], but it can be greater than one if there is a significant optical transition at an energy greater than is sampled by the ellipsometer [20]. Also, the exact value of e 1 (1) depends on the particular material.…”