Nano-phase separation of arsenic tri-sulphide (As2S3) film and its effect on plasma etching

Fabrication of As<inf>2</inf>S<inf>3</inf> Planar Waveguides with Very Low Propagation Loss

“…We reported [5] that As 2 S 3 film consists of As-As homopolar bond containing phases (e.g., As 4 S 4 ) interspersed with an orpiment-like backbone network. This phase separation can induce the volume scattering from the As 2 S 3 core.…”

“…The phase separation in As 2 S 3 film also result in rough and grainy surfaces when the film is etched in fluorine radicals-rich CF 4 -O 2 plasma due to the chemical etch rate differences among the phases [5]. From the device perspective, this rough surface causes light scattering in the waveguide.…”

“…Thermal annealing was applied to reduce the phase separation in asdeposited As 2 S 3 film [5]. CHF 3 was employed in plasma etching to attain a vertical pattern profile with smoother etched surface.…”

Solution phase driven As2S3 chalcogenide films: Optical and picosecond nonlinear optical properties

“…The bands near 234 cm À1 and 480 cm À1 correspond to As-As homopolar bonds and S-S stretching vibration in S 8 rings respectively. 32,33 We noticed that in bulk spectra peak near 480 cm À1 was absent but it is evident in the spin coated¯lm, due to the breaking of hetropolar bonds and the formation of homopolar bonds.…”

“…This peak is attributed to the presence of As 4 S 4 unit in thē lm along with the additional peaks near 310 and 380 cm À1 which were assigned to the asymmetric stretching mode of AsS 3 pyramids and As-S-As bridge, respectively. 32 It is also evident that with annealing at 150 C, intensity of band near 356 cm À1 is increased. The bands near 234 cm À1 and 480 cm À1 correspond to As-As homopolar bonds and S-S stretching vibration in S 8 rings respectively.…”