Polarimetry analysis and optical contrast of Sb₂S₃ phase change material

Abstract

Phase-change materials (PCMs) are the cornerstone for the development of reconfigurable and programmable photonic devices. Sb2S3 has been recently proposed as an interesting PCM due to its low-losses in the visible and near-IR. Here, we report the use of imaging polarimetry and spectroscopic ellipsometry to reveal and directly measure the optical properties of Sb2S3 both in crystalline and amorphous states obtained upon crystallization by annealing in the air of chemical bath deposited amorphous Sb2S3. The Mueller Matrix polarimetric analysis reveals the strong anisotropy of the Sb2S3 crystallites which crystallize in radial spherulitic domains in contrast to the optical isotropy of the amorphous films. A refractive index contrast of Δn = 0.5 is demonstrated while maintaining low-losses at telecommunications C-band, i.e., λ = 1550 nm.

Glassy and liquid Sb2S3: insight into the structure and dynamics of a promising functional material

“…Amorphous a -Sb 2 S 3 thin films and antimony-containing bulk sulfide glasses reveal similar vibrational features. 2,88–92 Assuming trigonal antimony local coordination 27 and the above resemblance in Raman spectra, various DFT simulations have been carried out. Isolated pyramidal units SbS 3 H 3 , corner- CS-Sb 2 S 5 H 4 and edge-sharing ES-Sb 2 S 4 H 2 dimers of different conformation, and small rings, Sb 3 S 6 H 3 or Sb 6 S 12 H 6 , systematically reveal overestimated Sb–S stretching frequencies, centered at 320 ≤ 〈ν Sb–S max 〉 350 ≤ cm −1 , Fig.…”

“…Amorphous a-Sb 2 S 3 thin films and antimonycontaining bulk sulfide glasses reveal similar vibrational features. 2,[88][89][90][91][92] Assuming trigonal antimony local coordination 27 and the above resemblance in Raman spectra, various DFT Raman spectroscopy measurements show that the glass structure hardly evolves at T t T g ; a negligible red shift of the Sb-S stretching envelope can only be observed, Fig. 4(b).…”

Characterizing optical phase-change materials with spectroscopic ellipsometry and polarimetry

“…When substituting Te by lighter chalcogen atoms S and Se, the band gap of the PCM increases (e.g. energy band gaps for crystalline Sb 2 Te 3 [25], Sb 2 Se 3 [26] and Sb 2 S 3 [14] are 0.22, 1.21,and 1.7 eV), leading the researcher focus into the investigation of low-loss PCMs in the visible and near-IR to fulfill the requirements for many optical frequencies operating reconfigurable photonic devices [9,10,13,27].…”

Pulsed laser deposition of Sb2S3 films for phase-change tunable nanophotonics

“…Unfortunately, its optical advantages come at the cost of a lower endurance (≈1000 cycles) [9,10], which arises from the gradual degradation of local atomic structure at the nucleation sites [11]. Other drawbacks are the highly polycrystalline character of Sb 2 S 3 after crystallization and its large inherent optical anisotropy [12][13][14], which can both negatively impact the desired functionalities of tunable nanostructures made of this material. While understanding the properties of individual crystal grains in Sb 2 S 3 films and the interplay of their structural and optical properties are still not fully clear [8], tunable color pixels and integrated waveguide switches have already been demonstrated [7,10,[15][16][17][18][19][20].…”