Enhanced optical properties of TiN-based spectrally selective solar absorbers deposited at a high substrate temperature

Optical Properties and Microstructure of TiNxOy and TiN Thin Films before and after Annealing at Different Conditions

“…The SS substrate showed (111) peak at angle 2θ = 44.49. Different angles of TiN peaks are reported in literature [12,16,24,29] (as shown in Table 2), this is probably due to the different stichometry of TiN structure obtained from different manufacturing techniques of thin film. The lattice parameter of the as-deposited TiN with an austenitic microstructure was calculated by Bragg's Law for the (111), (200), and (220) peaks and was found to be 3.6 Å [29].…”

“…Annealing was also shown as an additional postdeposition treatment, which can be used to optimize the properties and reduce the stresses and lattice defects induced during deposition. However, the literature contained contradictory reports about the effect of annealing on electrical and optical properties [16,24]. Popovic et al [16] annealed deposited TiN thin films at 600 • C and 700 • C in nitrogen ambient and vacuum furnace, and it was found that the annealing process resulted in a decrease in the absorption coefficient and the optical properties of the TiN thin film, compared to the as-deposited state.…”

“…Popovic et al [16] annealed deposited TiN thin films at 600 °C and 700 °C in nitrogen ambient and vacuum furnace, and it was found that the annealing process resulted in a decrease in the absorption coefficient and the optical properties of the TiN thin film, compared to the as-deposited state. Gao et al [24] proposed heating the substrate for annealing to 300 °C before depositing the TiN thin film and it was found that after heating the substrate, the thin film exhibits an absorbance of about 0.92 and an emittance equal to 0.11. The most predominant peak was (200) for all TiN samples and was (111) for the TiNxOy.…”

“…Several studies investigated the structure evolution and electrical properties of TiN thin films produced by different deposition parameters [13][14][15][16][17][18][19][20]. Several researchers have suggested [10,[21][22][23][24] that TiN may be used as an absorber layer for high-temperature applications; however, limited work appears in literature on the optical properties of TiN as a selective absorber [21][22][23][24]. TiN x O y had captured attention in the last decades, although TiN has almost the same properties, as will be proven in this work in addition to other advantages regarding its stability at higher temperatures and ease of preparation.…”

Structure, optical simulation and thermal stability of the HfB2-based high-temperature solar selective absorbing coatings

“…The SSAC is essentially an optical lm, which requires high absorptance and low emittance. 3,4 The absorption mechanism of SSAC strongly depends on the macroscopic and microscopic physical properties for a solid thin lm. Optical constants (refractive index n and extinction coefficient k) are essentially important parameters to understand the optical properties of the materials.…”