In situspectroscopic ellipsometry as a versatile tool for studying atomic layer deposition

Abstract

Basics of ALD Atomic layer deposition (ALD) is a low temperature vapor-based deposition technique for ultrathin and conformal film growth with submonolayer growth control use saturative surface reactions to ensure self-limiting film growth

Optoelectronic properties ofTa3N5: A joint theoretical and experimental study

“…3,30,31 This parameter was fixed because it is the first feature, correlates with the Tauc-Lorentz oscillator occurring at a peak transition energy of ∼ 4 eV and agrees with previous literature findings. 30,46 Furthermore, the next transition occurring at E g = 2.44 also agrees with the BSE/G 0 W 0 optical spectra (shown in Figs. 4 and 5) and the absorption feature seen in Ref.…”

“…5) and with previous literature findings. 46 Finally, a fourth transition can be inferred from the parameterization that occurs at an E g of 3.74 eV. Figure 5 shows good agreement for the real and imaginary parts of the dielectric function of Ta 3 N 5 without voids obtained from parameterization of spectroscopic ellipsometry data and those computed by theory, where the three transitions occurring at 2.1, 2.44 and 3.32 eV are direct.…”

“…23 In the case of Ta 3 N 5 , the n-type doping concentration is rather high due to reduced Ta species from N 3− anion vacancies, hence free carrier absorption is a valid assumption. 30,45 Free carrier absorption is generally visible at low energies down to the infrared 46 and below the bandgap. The Drude model for intraband absorption is given by…”

“…Multiple Tauc-Lorentz oscillators were used to parameterize the various electronic transitions occurring in Ta 3 N 5 . 46 Since the thickness of the film in question is known and held as a fixed parameter, direct numerical inversion (point-by-point fit) of the ellipsometry data was performed to first extract the dielectric function. 46,50 The optical model-derived dielectric function could then be compared to the direct inversion one.…”

“…46 Since the thickness of the film in question is known and held as a fixed parameter, direct numerical inversion (point-by-point fit) of the ellipsometry data was performed to first extract the dielectric function. 46,50 The optical model-derived dielectric function could then be compared to the direct inversion one. The mean square error (MSE) figure of merit was used to determine the quality of the model fit to the experimental Ψ and ∆ values.…”