Search for: All records

Due to its refractory properties and higher oxidation resistance, iridium (Ir) exhibits great potential for applications such as thermophotovoltaic emitters or contamination sensing. However, the lack of its temperature-dependent optical data prevents accurate modeling of Ir-based optical devices operating at higher temperatures. In this work, refractive indices of as-deposited and annealed Ir films, sputter-deposited, are characterized at between room temperature and 550°C over 300 nm to 15 µm of wavelength. The extinction coefficients of both as-deposited and annealed Ir films tend to decrease as temperature increases, with the exception of as-deposited Ir at 550°C due to significant grain growth. Under 530°C, optical constants of as-deposited Ir are less sensitive to temperature than those of annealed Ir. These characteristics of Ir films are correlated with their microstructural changes. 

Variable‐angle spectroscopic ellipsometry is used to determine the room temperature complex refractive index of molecular beam epitaxy grown GaSb_1−xBi_xfilms withx ≤ 4.25% over a spectral range of 0.47–6.2 eV. By correlating to critical points in the extinction coefficientk, the energies of several interband transitions are extracted as functions of Bi content. The observed change in the fundamental bandgap energy (E₀, −36.5 meV per %Bi) agrees well with previously published values; however, the samples examined here show a much more rapid increase in the spin‐orbit splitting energy (Δ₀, +30.1 meV per Bi) than previous calculations have predicted. As in the related GaAsBi, the energy of transitions involving the top of the valence band are observed to have a much stronger dependence on Bi content than those that do not, suggesting the valence band maximum is most sensitive to Bi alloying. Finally, the effects of surface droplets on both the complex refractive index and the critical point energies are examined.